COMPUTER NETWORKS

1) Define the  following:

 ARPANET - Networking started way back in 1969 with the development of the first network called the ARPANET. The U.S. department of defence sponsored a project named ARPANET (Advanced Research Projects Agency Network) whose goal was to connect computers at different universities and U.S. defence.

INTERNET - The world's largest network, the Internet. When networks at multiple locations are connected using services available from phone companies, people can send e-mail, share links to the global Internet, or conduct video conferences in real time with other remote users.

INTERSPACE - A client/server software program that allows multiple users to communicate online with real time audio, video and text chat in dynamic 3D environments.

CHANNEL - A medium that is used in the transmission of a message from one point to another.

Bandwidth(khz,mhz,ghz)- The range of frequencies available for transmission of data.

Data transfer rate(bps,kbps,mbps,gbps,Tbps)- The data transfer rate (DTR) is the amount of data in digital form that is moved from one place to another in a given time on a network.

2) Keeping in view the design of the network for an establishment or institution , in what situations would you suggest each one of the following ? Justify

a) Twisted pair cable - This is one of the common forms of wiring in networks, especially in LANs and it consists of two insulated wires arranged in a regular spiral pattern (double helix). It is generally used for telephone communications in offices and also in modern Ethernet networks. It is easy to install, can carry signal over long distances, least expensive medium.

b)  coaxial cable - It is the most commonly used transmission media for LANs. It consists of solid wire cores surrounded by one or more foil or wire shields, each separated by some kind of plastic insulator. It is widely used for television signals and also by large corporations in building security systems. Multi channel television signals can be transmitted around metropolitan areas at considerably less cost.

i) Better than twisted pair

ii) Suited for broadband transmission\

iii)Higher bandwidth

iv)basis for shared cables

c) Optical fibre - These consists of thin strands of glass or glass like material which are so constructed that they carry light from a source at one end of the fibre to a detector at the other end.

i)                    immune to electrical interference

ii)                  suitable for harsh industrial environment

iii)                expensive

iv)                suitable for broadband transmission

v)                  secured transmission

d) Infrared - Infrared is the frequency of light that is not visible to human eye. It has a range of wavelengths. These shorter wavelengths are the ones used by your TV remotes. playing an important role in wireless data communication due to the popularity of laptop computers , personal digital assistants(PDAs) , digital cameras , mobile phones , pagers and other devices but being a line-of-sight transmission , it is sensitive to fog and other atmospheric conditions.

i)short range medium of communication

ii)Inexpensive

e)radio link - In case of radiowave transmission, certain radio frequencies are allocated to private/government organizations for direct voice communications. Each radio signal uses a different frequency and this differentiates it from others.

The transmitter takes some message, encodes it and then transmits it with radio wave. The receiver on

the other hand receives the radio waves and decodes it. Both the transmitter and the receiver use

antennas to radiate and capture the radio signal. Radio transmission is widely used by delivery

services, policemen, security personals etc.

1)      easy to communicate through radio waves in difficult terrains since there is no need of digging

and laying cables.

2)       Radio waves can travel through long distances in all directions. Also they can easily pass through

obstacles like a building so they can be used for both indoor and outdoor communication.

f) microwave link - This type of transmission uses high frequency radio signals to transmit

data through space. Like radio waves, microwaves can pass through obstacles viz. buildings,

mountains etc. Microwaves offer a line of sight method of communication. A transmitter and receiver of a microwave system are mounted on very high towers and both should be visible to each other (line of sight) In case of microwave transmission, curvature of the earth, mountains and other structures often block the line of sight.

i)                    Microwave transmission does not require the expense of laying cables

ii)                  Signals become weak after travelling a certain distance and so require amplification. To overcome this problem, repeaters are used at regular intervals (25-30 kms).  

iii)                No cables laid down.

g)Satellite link - Satellites are an essential part of telecommunications systems worldwide today. They can carry a large amount of data in addition to TV signals. Satellite communication is a special use of microwave transmission system. A satellite is placed precisely at 36000 km above the equator where its orbit speed exactly matches the earth's rotation speed. Hence it always stays over the same point with respect to the earth. This allows the ground station to aim its antenna at a fixed point in the sky.

i)        1 ) Satellite communication is very economical keeping in mind the fact that the area covered throughsatellite transmission is quite large.

ii)      Transmission is affected by weather conditions like rain, thunderstorm etc.

iii)    Placing the satellite into its orbit involves very high cost.

3) Suggest the applications to which each of these are used. Also mention the function of each with respect to networking.

a) Modem - A modem (Modulator - Demodulator) is a peripheral device that enables a computer to transmit data over, telephone or cable lines. It modulates an analogue carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. This is why modem is an acronym of MOdulator/DEModulator.

b) RJ45 connector – RJ-45 , short form of Registered Jack - 45 , is an eight wired connector that is used to connect computers on a local area network(LAN), especially Ethernet.

c)Ethernet card- An Ethernet card is a kind of network adapter and is also known as Network Interface Card (NIC). These adapters support the Ethernet standard for high-speed network connections via cables.

d)Router - A Router is a network device that works like a bridge to establish connection between two networks but it can handle networks with different protocols. For example a router can link an Ethernet network to a mainframe or to internet. If the destination is unknown to the router, it sends the traffic to another router which knows the destination. The data is sent to the router which determines the destination address (using logical address) and then transmits the data accordingly.

e)Switch -A switch is a device that is used to break a network into different sub-networks called subnet or LAN segments. This prevents traffic overloading on the network. Switches are another fundamental part of many networks because they speed things up. They allow different nodes of a network to communicate directly with one another in a smooth and efficient manner. In simple terms, a network switch is a small hardware device that joins multiple computers together within one local area network (LAN).

f)Gateway - A gateway is a network device that establishes an intelligent connection between a local network and external networks with completely different structures i.e. it connects two dissimilar networks. In simple terms, it is a node on a network that serves as an entrance to another network.

g) Wifi card - Wi-Fi cards are small and portable cards that allow your desktop or laptop computer to connect to the internet through a wireless network. Wi-Fi transmission is through the use of radio waves. The antenna transmits the radio signals and these signals are picked up by Wi-Fi receivers such as computers and cell phones equipped with Wi-Fi cards. These devices have to be within the range of a Wi-Fi network to receive the signals. The Wi-Fi card then reads the signals and produces a wireless internet connection.

h) Firewall - A firewall is hardware or software based network security system. It prevents unauthorized access (hackers, viruses, worms etc.) to or from a network. Firewalls are used to prevent unauthorized internet users to access private networks connected to the Internet. All data entering or leaving the Intranet pass through the firewall, which examines each packet and blocks those that do not meet the specified security criteria. A firewall filters both inbound and outbound traffic. A firewall may allow all traffic through unless it meets certain criteria, or it may deny all traffic unless it meets certain criteria.

4)Illustrate the following network topologies

 Bus - Bus topology is also known as Linear Topology. In this type of topology, each node attaches directly to a common cable which acts as the backbone and therefore functions as a shared communication medium onto which various nodes are attached.If the backbone cable fails, the entire network effectively becomes unusable

Star- A star network features a central connection point called a "hub node" to which all other nodes are connected by a single path. Each node has a dedicated set of wires connecting it to a central network hub. Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN. On the other hand if the hub fails, the entire network also fails.

Tree- Tree topology is a combination of bus and star topology. The network looks like an inverted tree with the central root branching and sub-branching down to the nodes. It integrates multiple star topologies together onto a bus.

5) Mention what factors should be kept in mind while laying out the above mentioned topologies.

   a)   To cut down on cable length by calculating total distance – bus is used

   b)    When length is not an issue, and when a server needs to be the central node – star is used 

6)What are the different types of network. Give examples of each.

PAN (Personal Area Network)

A Personal Area Network is a computer network organized around an individual person. Personal area networks typically involve a mobile computer, a cell phone and/or a handheld computing device such as a PDA. You can use these networks to transfer files including email and calendar appointments, digital photos and music.

Personal area networks can be constructed with cables or be wireless. USB and FireWire technologies often link together a wired PAN, while wireless PANs typically use bluetooth or sometimes infrared connections. Bluetooth PANs generally cover a range of less than 10 meters (about 30 feet).

LAN (Local Area Network)

In a LAN, network devices are connected over a relatively short distance. They are generally privately owned networks within a single building or campus, of up to a few kilometres in size. LANs can be small, linking as few as three computers, but often link hundreds of computers used by thousands of people.

Nowadays we also have WLAN (Wireless LAN) which is based on wireless . One LAN can even be connected to other LANs over any distance via telephone lines and radio waves.

MAN (Metropolitan Area Network)

This is basically a bigger version of LAN and normally uses similar technology. It might cover few

buildings in a city and might either be private or public. This is a network which spans a physical area ( in the range of 5 and 50 km diameter) that is larger than a LAN but smaller than a WAN. MANs are usually characterized by very high-speed connections using optical fibres or other digital media and provides uplink services to wide area networks (WANs) and the Internet.

WAN (Wide Area Network)

As the term implies, WAN spans a large geographical area, often a country or a continent and uses various commercial and private communication lines to connect computers. Typically, a WAN combines multiple  LANs that are geographically separated. This is accomplished by connecting the different LANs using services such as dedicated leased phone lines, dial-up phone lines, satellite links, high speed fibre optic cables and data packet carrier services.

7)What is

TCP/IP - Transmission Control Protocol / Internet protocol(TCP/IP). The Transmission Control Protocol(TCP) breaks the data into packets that the network can handle efficiently. It manages the assembling of a message or file into smaller packets that are transmitted over the Internet. The Internet Protocol(IP)handles the address part of each packet so that it reaches to the right destination. It gives distinct address (called IP address) to each data packet.

FTP - File Transfer protocol - FTP is based on Client/Server principle. By giving the ftp command with any remote address, the file transfer can be initiated. In any FTP interface, clients identify the FTP server either by its IP address (such as 192.168.0.1) or by its host name (such as ftp.about.com). It is an efficient means to send and receive files from a remote host. You can even download programs by making FTP requests through your web browser.By logging on to an FTP server, you can delete, rename, move, or copy files at a  server.

PPP- Point to Point Protocol - PPP (Point-to-Point Protocol) is used for communication between two computers using a serial interface, mostly a personal computer connected by phone line to a server. For example, an Internet ServiceProvider(ISP) may provide you with a PPP connection so that the ISP'sserver can respond to your  requests, pass them on to the Internet, and forward your requested Internet responses back to you. It was basically designed to help communication between two systems through telephone lines as it supports transmission of network packets over a serial point to point link.

SMTP -  Simple Mail transfer protocol - SMTP stands for Simple Mail Transfer Protocol that allows transmission of email over the Internet. Most email software is designed to use SMTP for communication purposes when sending email. It only works for outgoing messages. So when an email has to be sent, the address of their Internet Service Provider's SMTP server has to be given.

One of the purposes of an SMTP is that it simplifies the communication of email messages between servers. It allows the server to break up different parts of a message into categories the other server can understand. Any email message has a sender, a recipient or sometimes multiple recipients - a message body, and usually a title heading.

POP3- Post Office Protocol Version 3- POP3 makes it easy for anyone to check their email if their email program is configured properly to work with the protocol. It is extremely common among most mail servers because of its simplicity and high success rate and minimumerrors. Also it can work with virtually any email program, as long as the email program is configured to host the protocol. The individuals receiving POP3 email will have to input their username and password in order to successfully receive email.

VOIP - VOIP stands for voice over internet protocol. It enables the transfer of voice using packet switched network rather than using public switched telephone network. By using VOIP software, phone calls can be done using standard internet connection.

Remote Login(Telnet) - Telnet is the main internet protocol for creating a connection with a remote machine. It allows you to connect to remote computers (called remote hosts) over a TCP/IP network (such as the Internet). Once your telnet client establishes a connection to the remote host, your client becomes a virtual terminal, allowing you to communicate with the remote host from your computer with whatever privileges you may have been granted to the specific application and data on that host computer.

Chatting

 A real time informal communication over the Internet is chatting. A chat program is software which is required for chatting over the internet. AOL Instant Messenger, Campfire, Internet Messenger, MSN Messenger are some commonly used chat programs.

 Internet Relay Chat (IRC)

IRC protocol is used for chatting. It provides chatting between a group or between two individuals. It is based on client/server model. The IRC client sends and receives messages to and from an IRC server. The IRC server transports the message from one client to another.

8) Wireless protocols     

GSM

The 2G system was based on GSM technology. GSM standard was defined by ETSI in 1989. GSM stands for Global System for Mobile Communication. GSM technology is a combination of FDMA and TDMA. With GSM, all subscriber and wireless provider information is stored on interchangeable modules known as SIM (Subscriber Identification Module) cards. By swapping out the SIM card, users can painlessly switch phones or providers. They used circuit switching.

CDMA

It stands for Code Division Multiple Access. In this, each user is allocated a unique code sequence. On the sender's end, the data signal is encoded using the given unique code. The receiver decodes the signal according the unique code and recovers the original data.

This allows multiple signals from different users to share the same frequency band. Because of this feature,  it is commonly called CDMA (Code Division Multiple Access).

WLL

Wireless in Local Loop(WLL) is meant to serve subscribers at homes or offices. In WLL services, the telephone provided is expected to be as good as wired phone.  WLL is analogous with local telephone service, but much more capable. A WLL system serves a local area by deploying a multiplicity of multichannel transmit/receive base stations(transceivers) that are within line-of-site of the intended customers.

GPRS - Data services have become a much more important part of the mobile phone network than they used to be, starting with text messaging and early packet data services such as GPRS (General Packet Radio Service).

9)What is the difference between 1G, 2G, 3G and 4G mobile telecommunication technologies?

1G - The first mobile system was devised in the U.S. by AT&T.AMPS (Advanced Mobile Phone System), invented by Bell Labs.It was based on the analog cellular technology. They only had voice facility available.

2G - Second-generation mobile phone systems switched to transmitting voice calls in digital form to increase capacity, improve security, and offer text messaging.It was based on GSM (Global System for Mobile communications). It used narrowband TDM (Time Division Multiplexing). The handset activated chip a SIM card, short for Subscriber Identity Module.

Data services have become a much more important part of the mobile phone network than they used to be, starting with text messaging and early packet data services such as GPRS (General Packet Radio Service) in the GSM system.

3G - The third generation of mobile phones, or 3G as it is called, is all about digital voice and data.

The following are the features:

 1. High-quality voice transmission.

2. Messaging (replacing email, fax, SMS, chat, etc.).

3. Multimedia (playing music, viewing videos, films, television, etc.).

4. Internet access (Web surfing, including pages with audio and video).

Many operators have taken cautious steps in the direction of 3G by going to what is sometimes called 2.5G, although 2.1G might be more accurate. One such system is EDGE (Enhanced Data rates for GSM Evolution), which is just GSM with more bits per symbol.

4G- 4G cellular networks that are now being standardized under the name LTE (Long Term Evolution).

While 3G cellular networks are based on CDMA and support voice and data, 4G cellular networks will be based on OFDM with MIMO, and they will target data, with voice as just one application.

4G technologies that are faster and better are on the drawing board under the name of LTE (Long Term Evolution).

Some of the features of 4G include:

•      high bandwidth;

•      ubiquity (connectivity everywhere);

•      seamless integration with other wired and

•      wireless IP networks, including 802.11 access points; adaptive resource and spectrum management;

•      and high quality of service for multimedia.

10) What is the difference between

a) Circuit switching and Packet switching(different ways of sending data across the network)

Circuit switching

Packet switching

Conceptually, when you or your computer places a telephone call, the switching equipment within the telephone system seeks out a physical path all the way from your telephone to the receiver’s telephone. When a call passes through a switching office, a physical connection is (conceptually) established between the line on which the call came in and one of the output lines. Nevertheless, the basic idea is valid: once a call has been set up, a dedicated path between both ends exists and will continue to exist until the call is finished

With this technology, packets are sent as soon as they are available. There is no need to set up a dedicated path in advance, unlike with circuit switching.  Packet switching networks place a tight upper limit on block size, allowing the packets to be buffered in main memory instead of on disk. They are well suited in handling interactive traffic

b) Wi-fi and Wi-max

Wi-fi	Wi-max
There is a standard for wireless LANs called IEEE 802.11, popularly known as WiFi, which has become very widespread. It runs at speeds anywhere from 11 to hundreds of Mbps.	IEEE formed a group to standardize a broadband wireless metropolitan area network.standardized as IEEE 802.16 and is popularly known as WiMAX(Worldwide Interoperability for Microwave Access).

c) Hacking and cracking

Hacking

Cracking

The term was used for people who engaged themselves in harmless technical experiments and fun learning activities. A computer enthusiast, who uses his computer programming skills to intentionally access a computer without authorization is known as hacking. The computer enthusiast involved in this activity is known as a hacker. A hacker accesses the computer without the intention of destroying data or maliciously harming the computer.

Another term commonly used with hacking is cracking. Cracking can be defined as a method by which a person who gains unauthorized access to a computer with the intention of causing damage.

11) What are the threats of computer networks? What are the damages caused? How do you prevent it?
Viruses are a  form of malicious code  that attaches itself to the host program When a virus arrives, either via a Web page, an email attachment, or some other way, it usually starts out by infecting executable programs on the disk.

Worms are like viruses that would replicate itself in seconds on every machine it could gain access to. But unlike viruses, it does not need to attach itself to a host program.

Once running, it connects to the machine from which it came, uploads the main worm, and executes it. After going to some trouble to hide its existence, the worm then looks through its new host's routing tables to see what machines that host was connected to and attempts to spread the bootstrap to those machines.

A very common practice is to write some genuinely useful program and embed the malware inside of it. Games, music players, and anything with splashy graphics are likely candidates.

People will then voluntarily download and install the application. As a free bonus, they get the malware installed, too. This approach is called a Trojan horse attack,

When the free program is started, it calls a function that writes the malware to disk as an executable program and starts it. The malware can then do whatever damage it was designed for, such as deleting, modifying, or encrypting files.

Electronic junk mail (spam) has become a part of life because spammers have collected millions of email addresses and would-be marketers can cheaply send computer-generated messages to them. The resulting flood of spam rivals the flow messages from real people.

Phishing messages masquerade as originating from a trustworthy party, for example, your bank, to try to trick you into revealing sensitive information, for example, credit card numbers. Identity theft is becoming a serious problem as thieves collect enough information about a victim to obtain credit cards and other documents in the victim’s name.

Small files called cookies that Web browsers store on users’ computers allow companies to track users’ activities in cyberspace and may also allow credit card numbers, social security numbers, and other confidential information to leak all over the Internet.

    12) What is the role of firewall in networks?

The ability to connect any computer, anywhere, to any other computer, anywhere, is a mixed blessing. While there is a lot of valuable material on the Web, being connected to the Internet exposes a computer to two kinds of dangers: incoming and outgoing.

 Incoming dangers include crackers trying to enter the computer as well as viruses, spyware, and other malware.

 Outgoing dangers include confidential information such as credit card numbers, passwords, tax returns, and all kinds of corporate information getting out.

Consequently, mechanisms are needed to keep "good" bits in and "bad" bits out. One approach is to use a firewall, which is just a modern adaptation of that old medieval security standby: digging a deep moat around your castle.

It is hardware or software based network security system. It prevents unauthorized access (hackers, viruses, worms etc.) to or from a network.

13)What is the importance of cyber law with respect to networks?

Is a generic term which refers to all the legal and regulatory aspects of Internet and world wide web.

Cyberlaw is important because it touches almost all aspects of transactions and activities on and concerning the internet, the world wide web and cyberspace.

   14) Write 2 sentences about India IT Act

In India, the cyber laws are contained in the Information Technology Act ,2000(IT Act 2000) .

It aims to provide the legal infrastructure for e-commerce in India by governing the transactions through the internet and other electronic medium.

15)  Write 1 or 2 lines about

Digital Signature - A digital signature is a mathematical scheme for demonstrating the authenticity of digital messages or documents. A valid digital signature gives a recipient reason to believe that the message was created by a known sender (authentication), that the sender cannot deny having sent the message (non-repudiation), and that the message was not altered in transit (integrity)

Cookies - Small files called cookies that Web browsers store on users’ computers allow companies to track users’ activities in cyberspace and may also allow credit card numbers, social security numbers, and other confidential information to leak all over the Internet.

IPR issues - The Intellectual Property may be defined as a product of the intellect that has commercial value, including copyrighted property such as literary or artistic works and ideational property.

16)What is Spam? How do you avoid it?

Electronic junk mail (spam) has become a part of life because spammers have collected millions of email addresses and would-be marketers can cheaply send computer-generated messages to them. The resulting flood of spam rivals the flow messages from real people.

Filtering software is able to read and discard  the spam generated by other computers, with lesser or greater degrees of success.

17)   Expand and explain the following

1) WWW - The world wide web (www) is a set of protocols that allows you to access any document on the Net through a naming system based on URLs.

Internet is a highway that offers lot many services, features etc. WWW is a small part of Internet. It is a truck that uses this highway.

2)           

HTML-Everything that you see on the web is documents written in a special language called HTML or Hypertext Markup Language.

This language tells browsers like Chrome how to display text, pictures and links on the screen.

       3)XML – Extensible Markup Language . markup language for documents containing structured information. Provides a facility to define tags and structural relationship b/w them

       4) HTTP-One widely used application protocol is HTTP (Hyper Text Transfer Protocol), which is the basis for the World Wide Web. When a browser wants a Web page, it sends the name of the page it wants to the server hosting the page using HTTP. The server then sends the page back.

       5)URL - Each page is assigned a URL (Uniform Resource Locator) that effectively serves as the page’s worldwide name. URLs have three parts: the protocol (also known as the scheme), the DNS name of the machine on which the page is located, and the path uniquely indicating the specific page (a file to read or program to run on the machine). In the general case, the path has a hierarchical name that models a file directory structure.

As an example, the URL of the page shown as follows

http://www.cs.washington.edu/index.html

This URL consists of three parts: the protocol (http), the DNS name of the host

(www.cs.washington.edu), and the path name (index.html).

18) Web site, Web browser, Web Servers, Web Hosting

 Web site - A location on a net server is called a web site. Each web site has a unique address called URL(Uniform Resource Locator) i.e. the web site of microsoft has an address www.microsoft.com

Web browser and web server - The world wide web (www) is based on clients and servers. A WWW client is called Web browser or simply a browser and WWW server is called a Web server.

Web Hosting  -  Means of hosting web-server application on a computer system through which electronic content on the internet is readily available to any web-browser client.

Web Scripting – Client Side – software used - VBScript, Javascript

Web Scripting – Server Side – software used -  ASP, PHP, PERL, JSP etc

AJAX - Web applications need responsive user interfaces and seamless access to data stored on remote Web servers. These technologies are commonly used with several other key technologies in a combination called AJAX (Asynchronous JAvascript  and Xml).

19) What is Web 2.0 for social networking?

Web 2.0 is the term given to describe a second generation of the World Wide Web that is focused on the ability for people to collaborate and share information online.

Web 2.0 basically refers to the transition from static HTML Web pages to a more dynamic Web that is more organized and is based on serving Web applications to users.

20) Explain

https: Hypertext with security . eg: https://www.bank.com/accounts/

When the Web burst into public view, it was initially used for just distributing static pages. However, before long, some companies got the idea of using it for financial transactions, such as purchasing merchandise by credit card, online banking, and electronic stock trading. These applications created a demand for secure connections. In 1995, Netscape Communications Corp., the then-dominant browser vendor, responded by introducing a security package called SSL (Secure Sockets Layer) to meet this demand.

E-commerce - Using computer networks, manufacturers can place orders electronically as needed. This reduces the need for large inventories and enhances efficiency.

As with companies, home users can access information, communicate with other people, and buy products and services with e-commerce.

Home shopping is already popular and enables users to inspect the online catalogs of thousands of companies.

Another area in which e-commerce is widely used is access to financial institutions.

Many people already pay their bills, manage their bank accounts, and handle their investments electronically.

Mobile Processor: A CPU chip designed for laptops, tablets, smartphones and other portable devices. Mobile processors use lower voltages and are designed to run cooler than the CPUs in desktop computers.

Today’s smartphone and mobile processors are very powerful, so powerful that it is almost as powerful as a desktop computer.

Mobile Banking: Mobile banking is a service provided by a bank or other financial institution that allows its customers to conduct financial transactions remotely using a mobile device such as a smart phone or tablet. Unlike the related internet banking it uses software, usually called an app, provided by the financial institution for the purpose. Mobile banking is usually available on a 24-hour basis. Some financial institutions have restrictions on which accounts may be accessed through mobile banking, as well as a limit on the amount that can be transacted.

Online banking: A method of banking in which transactions are conducted electronically over the Internet. Online banking refers to banking services where depositors can manage more aspects of their accounts over the Internet, rather than visiting a branch or using the telephone.

Payment apps: Apple Pay

Apple Pay works with iPhone, iPad, and Apple Watch. If a POS system supports Apple Pay, when you're ready to check out, you can use your stored credit or debit card to pay with just a quick press of your fingerprint or the side button on your watch. Mac computers can use Apple Pay too.

Samsung Pay & Android Pay:Similar to Apple Pay is Samsung Pay, which works with Samsung Galaxy devices. Android Pay is an app available on all non-rooted Android devices, available on Google Play. Tons of banks are supported and you can pay in lots of stores.

Bank Apps:Lots of banks let you transfer money to other users of that same bank. Sometimes, this feature is available from within the mobile app. Bank of America, Simple, Wells Fargo and Chase are just a few examples but there are many others that work the same way

Payment Services: A payment service provide .According to Wikipedia, the definition of a (PSP is a company that “offers shops online services for accepting electronic payments by a variety of payment methods including credit card, bank-based payments such as direct debit, bank transfer, and real-time bank transfer based on online banking. 

Exercises to work: P-808 Q11,12,16,17,34,35,36,37,38,41,p-827 Q19,20,9-831-Q19,20