Networks and Internet

The request/response protocol that powers the web — how browsers and servers talk to each other.

A numeric identifier for a network interface — how computers find each other on the internet.

A small, self-describing chunk of data that travels across a network. The internet's fundamental unit of communication.

A device that forwards IP packets between networks, deciding which neighbour gets each packet on its way to the destination.

The phone book of the internet — translates human-readable names like example.com into IP addresses.

A reliable, ordered, stream-based transport protocol on top of IP. The plumbing under most internet traffic.

The protocol that encrypts and authenticates almost all secure traffic on the internet — the "S" in HTTPS, IMAPS, SMTPS, and many more.

A connectionless, "fire and forget" transport protocol. Faster than TCP but with no delivery, ordering, or reliability guarantees.

A global network of edge servers that caches and serves content close to users — making the web feel fast from anywhere on Earth.

HTTP wrapped in TLS — the encrypted, authenticated version of the web's core protocol, now the default for every public site.

A seven-layer conceptual model for how networking protocols stack on top of each other — physical wires at the bottom, applications at the top.

An architectural style for HTTP-based APIs that models the world as named resources accessed via standard verbs — the dominant way services talk to each other on the web.

The OS abstraction that lets a program send and receive data over a network — the fundamental API sitting between application code and the TCP/IP stack.

A barrier that filters network traffic against a set of rules, allowing or blocking packets by address, port, or protocol to protect a network or host.

A network node that bridges two different networks — most commonly the "default gateway," the router that forwards traffic from your local network out to the rest of the internet.

Network Address Translation — how a router lets many devices on a private network share one public IP address by rewriting addresses and ports on traffic passing through it.

A protocol that upgrades an HTTP connection into a full-duplex, persistent channel for sending messages back and forth in real time.

The protocol that automatically assigns IP addresses, subnet masks, gateways, and DNS servers to devices when they join a network — the reason you don't manually configure an IP every time you connect to Wi-Fi.

Advertising the same IP address from multiple locations so BGP routes each user to the nearest one — the mechanism behind Cloudflare's global network, 1.1.1.1, and the DNS root servers.

The successor to IPv4 that expands the address space from 4 billion to 340 undecillion addresses — ending address exhaustion, simplifying routing, and building security and auto-configuration into the protocol.

A transport protocol built on UDP that combines TCP's reliability with TLS's encryption in a single handshake — eliminating head-of-line blocking and reducing connection setup latency.

The routing protocol that holds the internet together — autonomous systems exchange reachability information so each router knows how to forward packets to any IP address on earth.

A routing technique that forwards packets by swapping short labels instead of looking up IP addresses — enabling traffic engineering, VPNs, and predictable paths across carrier networks.