Networks and Internet
How computers talk — protocols, the internet, DNS, HTTP, and the web.
Networks and the internet are how independent computers cooperate. The section spans physical links, packets and protocols, DNS and routing, and the web on top.
Core
The essentials. Start here.-
HTTP
The request/response protocol that powers the web — how browsers and servers talk to each other.
core beginner protocol -
IP Address
A numeric identifier for a network interface — how computers find each other on the internet.
core beginner concept -
Packet
A small, self-describing chunk of data that travels across a network. The internet's fundamental unit of communication.
core beginner concept -
Router
A device that forwards IP packets between networks, deciding which neighbour gets each packet on its way to the destination.
core beginner technology -
DNS
The phone book of the internet — translates human-readable names like example.com into IP addresses.
core intermediate protocol -
TCP
A reliable, ordered, stream-based transport protocol on top of IP. The plumbing under most internet traffic.
core intermediate protocol -
TLS
The protocol that encrypts and authenticates almost all secure traffic on the internet — the "S" in HTTPS, IMAPS, SMTPS, and many more.
core intermediate protocol -
UDP
A connectionless, "fire and forget" transport protocol. Faster than TCP but with no delivery, ordering, or reliability guarantees.
core intermediate protocol
Important
What you'll meet next.-
CDN
A global network of edge servers that caches and serves content close to users — making the web feel fast from anywhere on Earth.
beginner technology -
HTTPS
HTTP wrapped in TLS — the encrypted, authenticated version of the web's core protocol, now the default for every public site.
beginner protocol -
OSI Model
A seven-layer conceptual model for how networking protocols stack on top of each other — physical wires at the bottom, applications at the top.
beginner concept -
REST API
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.
beginner concept -
Socket
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.
beginner concept -
Firewall
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.
intermediate concept -
Gateway
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.
intermediate concept -
NAT
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.
intermediate concept -
WebSocket
A protocol that upgrades an HTTP connection into a full-duplex, persistent channel for sending messages back and forth in real time.
intermediate protocol
Supplemental
Niche, historical, or specialized.-
DHCP
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.
supplemental beginner protocol -
Anycast
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.
supplemental intermediate concept -
IPv6
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.
supplemental intermediate protocol -
QUIC
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.
supplemental intermediate protocol -
BGP
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.
supplemental advanced protocol -
MPLS
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.
supplemental advanced protocol