Introduction
A protocol is the agreed set of rules two devices follow to communicate — but different tasks (browsing, emailing, transferring files) each need their own specialised set of rules. This topic introduces the standard protocol for one of those tasks: remote login.
Concept
TELNET is the protocol used to log into a remote computer system over a network, as if you were sitting directly in front of it, and operate it from your own machine.
Explanation
TELNET is one of the oldest Internet protocols, and it's still the standard exam answer whenever a question describes "logging into a remote system" or "remote terminal access" — it's specifically about controlling another computer, not transferring files (that's FTP) or sending mail (that's SMTP).
Note: TELNET sends data, including any password you type, without encryption — which is exactly why SSH (Secure Shell) has replaced it for anything sensitive today. SSH does the same job, encrypted.
Summary
TELNET is the protocol used for remote login — accessing and controlling another computer over a network as if you were physically at its keyboard.
1. TCP/IP (Transmission Control Protocol / Internet Protocol)
This is the fundamental suite of protocols that makes the Internet work. It is actually two protocols working together.
| TCP | Transmission Control Protocol: It breaks the data into small "packets" before sending and reassembles them at the destination. It ensures data is delivered correctly (Reliable). |
| IP | Internet Protocol: It handles the "Addressing." It ensures the packets are routed to the correct computer (IP Address). |
2. Web & File Transfer
HTTP (HyperText Transfer Protocol)
The standard protocol for transferring web pages (HTML files).
Risk: Data is sent in plain text (Not secure).
HTTPS (HyperText Transfer Protocol Secure)
The secure version of HTTP. It uses SSL/TLS encryption.
Exam Note: Always used for Banking/Transactions.
FTP (File Transfer Protocol)
Used specifically for uploading and downloading files to/from a server.
3. Email Protocols
| Protocol | Full Form | Direction (Crucial) |
|---|---|---|
| SMTP | Simple Mail Transfer Protocol |
SENDING (Pushing). Used when you click "Send". It pushes mail to the server. |
| POP3 | Post Office Protocol (v3) |
RECEIVING (Pulling). Used when you open your inbox. It pulls mail from the server. |
4. Access & Communication
Introduction
Beyond TELNET, a handful of other protocols each own one specific job on the Internet — email, file transfer, secure browsing, and the basic point-to-point link your Internet Service Provider uses to connect you at all.
Concept
- PPP (Point-to-Point Protocol) — establishes a direct connection between two nodes, commonly used by ISPs to connect a home or office to the Internet.
- SMTP (Simple Mail Transfer Protocol) — used for sending email.
- POP3 (Post Office Protocol) — used for receiving email.
- FTP (File Transfer Protocol) — used for uploading and downloading files between computers.
- HTTP (HyperText Transfer Protocol) — the standard rules a web browser and a web server follow to request and deliver web pages. It's what actually happens every time you open a website.
- HTTPS (HyperText Transfer Protocol Secure) — the encrypted version of HTTP, used for secure transactions like online banking or shopping.
Explanation
SMTP vs. POP3 is one of the most repeated pairs in this chapter, precisely because they sound similar but do opposite jobs: SMTP is the "outgoing mail" protocol (sending), POP3 is the "incoming mail" protocol (receiving) — remembering that direction is the whole question.
Tip: Any question mentioning "secure", "encrypted", or "safe online transaction" always points to HTTPS — the "S" at the end is literally short for Secure.
Summary
PPP connects you to your ISP; SMTP sends email while POP3 receives it; FTP moves files between computers; HTTP is the standard rule set behind every web page request, and HTTPS is its encrypted, secure version used for sensitive transactions.
Protocol Master Sheet
A complete detailed reference of every protocol in the syllabus. Memorize the "Usage" column for 2-mark definitions.
| Acronym | Full Form | Detailed Usage & Description |
|---|---|---|
| TCP/IP | Transmission Control Protocol / Internet Protocol | The foundational protocol suite of the Internet. TCP is responsible for breaking data into packets and ensuring reliable delivery. IP handles the addressing and routing of packets to the correct destination. |
| HTTP | HyperText Transfer Protocol | The standard protocol used for transferring web pages (HTML documents) on the World Wide Web. It sends data in plain text, making it fast but unsecure for sensitive information. |
| HTTPS | HyperText Transfer Protocol Secure | The secure version of HTTP that uses SSL/TLS encryption. It ensures that data transferring between the browser and server is encrypted, making it essential for online banking and shopping. |
| FTP | File Transfer Protocol | A standard network protocol used specifically for the transfer of computer files between a client and server. It is the primary method for uploading websites or downloading large software files. |
| SMTP | Simple Mail Transfer Protocol | The standard protocol for SENDING emails. It "pushes" the email from the sender's client to the mail server, and then to the receiver's mail server. |
| POP3 | Post Office Protocol (Version 3) | The standard protocol for RECEIVING emails. It "pulls" the email from the mail server to the recipient's device. Usually, it downloads the mail and deletes it from the server. |
| PPP | Point-to-Point Protocol | A data link protocol used to establish a direct connection between two nodes. It is commonly used by Internet Service Providers (ISPs) to connect a customer's dial-up or broadband modem to the Internet. |
| TELNET | Telecommunication Network | A protocol used for Remote Login. It allows a user to log into a remote computer (server) and execute commands as if they were sitting directly in front of that computer. |
| VoIP | Voice over Internet Protocol | A technology that delivers voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet, rather than via the public switched telephone network (PSTN). |
Introduction
Protocols move data around, but "the web" itself is made of a few distinct pieces working together — the software you browse with, the machine that stores a website, and the service that makes it reachable by everyone.
Concept
- WWW (World Wide Web) — the interconnected system of web pages, linked together and accessible over the Internet using a Web Browser.
- Web Browser — the software used to view web pages (Chrome, Firefox, Edge).
- Web Server — the computer/software that stores web pages and delivers them to a browser whenever requested.
- Web Hosting — the service that makes your website's files available on a Web Server so it's accessible via the World Wide Web to anyone, anywhere.
Explanation
It's worth being precise about the difference between "the WWW" (the web itself, the interconnected system of pages) and "the Internet" (the underlying physical network of connected computers that makes the WWW possible) — the WWW is one service that runs on top of the Internet, not a synonym for it.
Note: Web Browser = the tool YOU use to view pages. Web Server = the machine that STORES and delivers pages. It's easy to swap these two in an exam answer if you're not careful about which direction the data is flowing.
Summary
The World Wide Web is the interconnected system of pages you access via a Web Browser; a Web Server stores and delivers those pages; Web Hosting is the service that puts your own website onto a server so it's reachable on the Web.
The World Wide Web (WWW)
The Internet is the hardware (cables, routers). The WWW is the software (pages, sites) that runs on top of it.
Definition: The WWW is a system of interlinked hypertext documents (web pages) accessed via the Internet. It uses the HTTP protocol.
Who does what?
Web Browser (Client)
The Requester.
It is a software application used to access and view websites. It sends a request to the server and displays the result code (HTML) as a readable page.
Examples: Google Chrome, Mozilla Firefox, Edge, Safari.
Web Server (Host)
The Provider.
It is a powerful computer (hardware) or software that stores website files (HTML, CSS, Images) and delivers them to the user's browser when requested.
Examples: Apache, Nginx, Microsoft IIS.
Storage & Structure
| Website | A collection of related web pages (HTML files) identified by a common Domain Name (e.g., amazon.com). |
| Web Hosting |
The service of renting space on a Web Server to store your website files so they are accessible on the internet 24/7.
Analogy: If the Website is your "House", Web Hosting is the "Land" you rent to build it on. |