Internet and Its Services

1. Introduction to the Internet

Definition: The Internet stands for "International Network." It is a global "network of networks" consisting of millions of private and public local-to-global networks.
Network Concept: A network is generally a group formed by connecting two or more computer systems together.
Father of the Internet: Vint Cerf, who started it in the year 1950.
How it Works (Protocols):
- Data available on the internet is controlled by protocols.
- TCP/IP: This protocol is used by all computers on the internet to communicate. It divides a file into several smaller parts using a file server, which are known as "packets".

2. History of the Internet

1969 - ARPANET: The Advanced Research Projects Agency Network (ARPANET) was launched. It connected the University of California (Los Angeles) and the University of Utah.
- Objective: To connect computers of various universities and the American Defense Department.
- Significance: It was the world's first packet-switching network.
Mid-1980s - NSFnet: The National Science Foundation created a high-capacity network called NSFnet, which was more capable than ARPANET.
- Limitation: It only allowed educational research and strictly prohibited private business/commercial use.
Birth of the Modern Internet: Because of NSFnet's restrictions, private organizations and individuals built their own networks, which later merged with ARPANET and NSFnet to form the Internet we use today.

3. Advantages and Disadvantages of the Internet

Advantages (Pros)	Disadvantages (Cons)
Global Reach: Allows you to easily contact anyone, anywhere in the world.	Security Risks: Highly responsible for spreading computer viruses.
Cost & Paper Saving: Publishing documents online saves paper and printing.	Privacy Issues: Messages sent over the internet can be easily stolen.
Business Resource: A valuable resource for companies to advertise and conduct transactions.	Misinformation: Much information is unverified and can be wrong or irrelevant.
Time Efficiency: Searching for the same information repeatedly takes less time.	Misuse: Unwanted/inappropriate elements can be used by malicious actors (like terrorists).
Convenience: Quick access to millions of pieces of information, audio, and video.	Cyber Fraud: Fraudsters can steal sensitive data like credit/debit card information.

4. Internet Connections

Choosing an internet connection primarily depends on two factors: Bandwidth (which determines speed) and Price.

A. Dial-up Connection

Uses existing pre-installed telephone lines to connect.
The modem dials the Internet Service Provider's (ISP) phone number to establish a connection.
Takes around 10 seconds to connect.
ISP (Internet Service Provider): Companies that provide internet services to users (e.g., Airtel, MTNL, Vodafone).

B. Broadband Connection

Used for high-speed internet access over telephone lines, offering much faster speeds than dial-up. It includes various high-speed transmission technologies:

DSL (Digital Subscriber Line): Transmits digital data over local copper telephone wires. Works similarly to dial-up but is significantly faster. Requires a DSL modem.
Cable Modem: Cable operators provide internet via coaxial cables. Transmission speeds are typically 1.5 Mbps or higher.
Fiber Optic: Converts data from electrical signals into optical (light) signals. Sends these light signals through transparent glass fibers (about the thickness of a human hair).
Broadband Over Power Line (BPL): Provides broadband service over low and medium-voltage electric power distribution networks. Best for: Rural areas where no other medium is available.

C. Wireless Connection

Uses radio links between the customer's location and the service provider, eliminating the need for cables or modems. Ideal for areas where DSL or cable cannot reach.

Wi-Fi (Wireless Fidelity): A universal technology using radio frequencies to transfer data without wires at high speeds. Common in restaurants, cafes, hotels, airports, etc..
WiMAX (World Wide Interoperability for Microwave Access): Designed to provide internet to residential and enterprise customers over greater distances and at higher speeds than Wi-Fi. Founded in June 2001 by the WiMAX forum.
Mobile Wireless Broadband: Provided by mobile and telephone service providers. Primarily for mobile subscribers, but generally offers much lower speeds.
Satellite: Provides necessary links for internet, telephone, and television services, playing a critical role in broadband.

5. Intranet, Extranet, and ISDN

Feature	Intranet	Extranet
Definition	A private computer network within a single organization.	A private network that extends securely to specific outside users.
Primary Users	Employees of the organization.	Vendors, partners, and customers.
Purpose	To share data internally, improve communication, and enhance collective knowledge.	To securely share business information and conduct trade with external partners.

ISDN (Integrated Services Digital Network): A digital telephone service used to transmit voice, data, and control information over a single telephone line. It is primarily used for large-scale commercial purposes.

6. Interconnecting Protocols

Protocols are sets of rules that manage data communication. Important internet protocols include:

TCP/IP (Transmission Control Protocol/Internet Protocol): Provides end-to-end connectivity, handles data formatting, and routing. It has two main parts:
- TCP: Breaks messages into packets at the sender's end and reassembles them at the receiver's end to recreate the message. It is a "Connection Oriented" protocol.
- IP: Establishes networks between computers to allow communication. It manages routing packets over the network, maintaining addresses based on standards (contains source and destination addresses).
FTP (File Transfer Protocol): Allows users to upload files from their computer to websites or download files from websites to their PC. Examples: Filezilla, Kasablanca, Konqueror.
HTTP (Hypertext Transfer Protocol): Ensures messages are formatted and transmitted correctly, and dictates the actions web servers and browsers should take. It is a "Stateless Protocol" because every command is executed independently.
HTML (Hypertext Markup Language): Used for designing web pages. It uses a set of markup tags (< >) to instruct the web browser on how to display text, images, etc., to the user.
Telnet Protocol: A network protocol using virtual connections to provide bi-directional, text-oriented communication over a Local Area Network (LAN). It requires a valid username and password to start a session.
Usenet Protocol: A decentralized protocol with no central server or administrator. It allows groups of internet users to exchange views and advice on specific topics.
PPP (Point to Point Protocol): A dial-up account that connects a computer directly to the internet using a modem. Data is sent at a speed of 9600 bits/second.
WAP (Wireless Application Protocol): Used in web browsers on mobile devices (WAP browsers) to provide web services.
VoIP (Voice Over Internet Protocol): Used to deliver voice communication over IP networks (e.g., IP calls).

7. Important Internet Related Terms

WWW (World Wide Web): Introduced on March 13, 1989, it is a system of internet servers that supports specially formatted documents (HTML) and links, along with graphics, audio, and video.
Web Server: A computer program connected to the internet that fulfills requests for HTML pages or files. Each has a unique IP address (e.g., Apache HTTP Server, Internet Information Services).
Web Address (URL - Uniform Resource Locator): Identifies the specific location of a web page on the internet. Created by Tim Berners-Lee in 1991.
- Example Breakdown of http://www.google.com/services/index.htm:
  - http = Protocol Identifier
  - www = World Wide Web
  - google.com = Domain Name
  - /services/ = Directory
  - index.htm = Web Page
DNS (Domain Name System): Translates domain names into numeric IP addresses (e.g., 204.157.54.9) so servers can be identified and located.
Blogs: A webpage or website containing a regular record of an individual's opinions, links to other sites, text, artistic pictures, photos, videos, and music.
Newsgroups: Online discussion groups that allow conversations via electronic bulletin board systems and chat sessions, hierarchically organized by topics and sub-topics.
Search Engine: A website used to find information regarding any topic on the internet. Examples: Google, Yahoo.

Classification: Web Pages & Web Browsers

Category	Types & Descriptions
Web Pages	Static: Displays the same content every time it is accessed. Dynamic: Content can change every time it is accessed.
Web Browsers	Text Web Browser: Displays only text-based information (e.g., Lynx). Graphical Web Browser: Supports both text and graphical information (e.g., Firefox, Chrome, Netscape, Internet Explorer).

Domain Name Extensions (Quick Reference)

Domain names locate computers connected to the internet. The last part of a domain identifies the organization type (usually 3 letters) or the country (usually 2 letters).

Extension	Organization / Country Type
.com	Commercial Institution
.gov	Government Institution
.edu	Educational Institution
.mil	Military Institution
.net	Network Resources
.org	Non-profit Organization
.info	Informational Organization
.in / .uk / .fr	India / United Kingdom / France

8. Internet Services

E-mail (Electronic Mail): Allows users to send/receive electronic messages worldwide. Requires a unique email address (format: username@domainname, e.g., xeeedbooks@gmail.com). Uses SMTP (Simple Mail Transfer Protocol).
Video Conferencing: Enables face-to-face conversations between distant individuals/groups. Requires high-speed internet, a camera, microphone, screen, and sound system.
E-learning: Computer and internet-based online education/training where information is provided electronically.
E-banking: Automated system allowing users to manage bank accounts, transfer funds, pay bills, and recharge mobiles from anywhere using an electronic device.
E-shopping: Online purchasing of goods (books, clothes, hardware, software, etc.). Payments are made via Cash on Delivery or E-banking.
E-reservation: Booking tickets (railways, airways) or hotel rooms online without waiting in counter queues.
Social Networking: Connecting with known or unknown individuals globally through text, pictures, or videos. Examples: Facebook, Myspace.
Chatting: Widespread text-based communication that also allows sharing of images, video, and audio. Examples: Skype, Yahoo Messenger.

E-commerce vs. M-commerce

Term	Definition
E-commerce	The transaction of goods, maintaining business relations, and sharing business information (including financial transactions) over the internet.
M-commerce	Performing all E-commerce activities (buying/selling) specifically using wireless mobile devices like smartphones and tablets.

9. Important Facts ("Also Know")

Googling: The act of searching for facts/information on the Google search engine.
POP3: The protocol used specifically to retrieve or extract emails.
Mouse Potato / Comp Head: A person who spends the majority of their time on a computer.
PHP (Hypertext Preprocessor): A coding language used to create international web pages.
Cookie: A small text message given by a web server to a web browser, which the browser stores as a text file.
Junk E-mail: Unwanted or unsolicited emails received against a user's wishes.

Summary / Quick Revision Notes

Internet Definition: International Network of Networks started in 1950 by Vint Cerf.
Core Protocol: TCP/IP controls data and splits files into "packets".
Key Milestones: ARPANET (1969, world's first packet-switching network) and NSFnet (mid-80s, restricted to education/research) paved the way for the modern internet.
ISPs: Airtel, MTNL, Vodafone provide your actual internet access.
Dial-up vs Broadband: Dial-up is slow and uses basic phone dialing; Broadband is high-speed (DSL, Cable, Fiber Optic).
Wireless Types: Wi-Fi (short range, public places), WiMAX (long distance, high speed), Mobile Broadband (cellular, slower), Satellite.
Intranet vs Extranet: Intranet is strictly internal for employees; Extranet is an internal network safely opened up to trusted partners and customers.
ISDN: Digital service transmitting voice and data over a single line for major commercial use.

TCP/IP is the core internet protocol: TCP breaks data into packets, and IP handles routing and addressing.
HTTP is stateless; HTML designs web pages using tags; FTP transfers files.
URL stands for Uniform Resource Locator and pinpoints web pages. It was created by Tim Berners-Lee (1991).
Domains indicate the entity type: .com (Commercial), .gov (Government), .edu (Education). DNS translates these into numeric IP addresses.
Emails require SMTP to send and POP3 to receive. They use the format username@domainname.
E-services make life easier by allowing online shopping (E-shopping), banking (E-banking), education (E-learning), and ticket booking (E-reservation).
M-Commerce is essentially E-commerce done via mobile/wireless devices.
Key trivia: A heavy computer user is a Mouse Potato; unwanted emails are Junk Mail; tracking files saved by your browser are Cookies.

Physics

Numeric