The Internet

The Internet is a global network enabling communication, information exchange, and digital services. It connects millions of private, public, academic, business, and government networks through a complex stack of digital protocols and physical infrastructure, including fiber optic cables, routers, and servers.

Key Aspects

The Internet Protocol Stack

Layer	Description
Application Layer	User-facing applications operate using common protocols HTTP, HTTPS, FTP, DNS, SMTP.
Transport Layer	Reliable data transmission between processes using protocols such as TCP, UDP, QUIC.
Network Layer	Addressing and routing of datagrams across networks - IP Internter Protocol.
Link Layer	Physical connection between devices (e.g., Ethernet, Wi-Fi).
Pyhsical Medium	Copper, Fiber, Wireless, etc.

Application Layer Protocols

• HTTP - (HyperText Transfer Protocol) A protocol used for transmitting web pages and other data over the Internet.
• HTTPS - (HyperText Transfer Protocol Secure)The secure version of HTTP, encrypting data with TLS.
• DNS - (Domain Name System)Translates human-readable domain names (example.com) into IP addresses (192.168.1.1).
• SMTP - (Simple Mail Transfer Protocol) Used for sending emails between mail servers.

Transport Protocols & Transport Layer Security

• TCP - Used for reliable data transmission over the Internet, ensuring packets arrive in order and without errors.
• UDP - Used for fast data transmission across networks.
• SSL & TLS - Cryptographic protocols that encrypt data to ensure secure communication over the Internet.

Internet Protocol

• IPv4 - (Internet Protocol Version 4), The older and widely used version of IP addressing. Uses 32-bit addresses.
• IPv6 (Internet Protocol Version 6), IPv6 is the latest version of the Internet Protocol. Uses 128-bit Addressing

Internet Protocol Types

• Interior Gateway Protocol - (IGP), A type of routing protocol used within a single autonomous system (AS).
• Exterior Gateway Protocol - (EGP), A type of routing protocol used to exchange routing information between different autonomous systems (ASes) on the Internet or large-scale networks.

Certificate Authorities

Certificate Authorities are trusted organizations that issue digital certificates. These certificates are used to verify the identity of websites, companies, and individuals online.