Ethernet: The wired foundation of local networks — framing, addressing, and switching at Layer 2.

ARP: Translates IP addresses to MAC addresses — the bridge between Layer 3 and Layer 2.

IPv4: The addressing system of the internet — every packet gets a source and destination IP.

IPv6: The next-generation internet addressing system — 128-bit addresses, simplified headers, and no more NAT.

OSPF: Link-state interior gateway protocol: every router builds an identical topology database, then runs Dijkstra to compute its routing table.

DNS: The internet's phone book — translates domain names to IP addresses.

BGP: The routing protocol of the internet — how autonomous systems find paths to each other.

ICMP: The diagnostic protocol behind ping and traceroute — how the network reports errors.

TCP: Guarantees ordered, reliable delivery of data between applications.

UDP: Fire-and-forget delivery — fast but with no guarantees.

QUIC: UDP-based transport with built-in encryption and multiplexing — the future of the web.

SCTP: Multi-streaming, multi-homing transport — TCP's more capable but less popular cousin.

MPTCP: TCP that uses multiple network paths simultaneously — WiFi and cellular at the same time.

HTTP/1.1: The original language of the web — one request at a time, in plain text.

HTTP/2: Multiplexed, binary HTTP — many requests flying over one connection simultaneously.

HTTP/3: HTTP over QUIC — faster connections, no head-of-line blocking, built-in encryption.

WS: Full-duplex, persistent connection — server and client talk freely in real time.

gRPC: High-performance RPC framework using Protocol Buffers over HTTP/2.

GraphQL: Ask for exactly the data you need — no more, no less. A query language for APIs.

SSE: One-way real-time streaming from server to browser over plain HTTP.

REST: An architectural style for web APIs — not a protocol, but the dominant pattern for HTTP services.

MCP: A universal interface that lets AI applications discover and use tools, data, and prompts from any server.

A2A: An open protocol that lets AI agents discover each other, delegate tasks, and collaborate — even across different frameworks and vendors.

JSON-RPC: A minimal RPC protocol encoded in JSON — call a method by name, get a result back. Nothing more.

SOAP: XML-based messaging for enterprise web services — structured envelopes, strict schemas, and built-in error handling.

MQTT: Lightweight publish/subscribe messaging — the lingua franca of IoT.

AMQP: Enterprise message queuing with routing, persistence, and guaranteed delivery.

CoAP: HTTP for tiny devices — REST semantics over UDP for constrained IoT.

STOMP: A dead-simple text protocol for message brokers — the HTTP of messaging.

XMPP: The open, XML-based messaging protocol born as Jabber — federated chat before it was cool.

Kafka: The distributed event streaming wire protocol — LinkedIn's answer to real-time data at massive scale.

WebRTC: Peer-to-peer audio, video, and data — directly between browsers, no plugins needed.

RTP: The standard way to deliver audio and video packets in real-time over UDP.

SIP: The "dialing" protocol for VoIP — establishes, modifies, and tears down calls.

HLS: Apple's adaptive streaming protocol — video delivered as small HTTP file downloads.

RTMP: The Flash-era streaming protocol that refused to die — still the king of live stream ingest.

SDP: The universal format for describing multimedia sessions — the matchmaker behind every WebRTC and VoIP call.

DASH: The open standard for adaptive video streaming — MPEG-DASH powers Netflix, YouTube, and the open web.

TLS: Encrypts everything between client and server — the lock icon in your browser.

SSH: Encrypted remote access — how developers securely connect to servers.

DHCP: Automatically assigns IP addresses — plug in and you're on the network.

NTP: Keeps every device on Earth synchronized to the same clock.

SMTP: The protocol that delivers email across the internet — store and forward, hop by hop.

FTP: One of the oldest internet protocols — built for transferring files between machines.

IMAP: Access and manage email on the server — read, search, and organize without downloading.

OAuth: Delegated authorization for the modern web — let apps access your data without sharing your password.

STUN/TURN/ICE: Lets two peers behind home routers find each other: STUN learns your public address, TURN relays when direct paths fail, and ICE picks the best working path.

IPsec: The IETF's Layer-3 cryptographic envelope — every site-to-site VPN, every 3GPP mobile-core backhaul, every IKEv2 client tunnel on macOS / iOS / Windows / Android runs IPsec.

WG: A ~4,000-line in-kernel VPN that does one thing — encrypted, authenticated, packet-routed IP tunnels — with a single, opinionated, modern crypto suite. The deliberate anti-IPsec.

mDNS / DNS-SD: DNS, shouted to a link-local multicast group, so every printer, Chromecast, AirPlay speaker, and Matter device on your LAN can find each other with zero configuration.

krb5: The three-headed dog that guards every Windows domain, every Hadoop cluster, every NFSv4-with-security mount on Earth. Tickets, not tokens; trusted third party; mutual authentication without ever sending the password.

802.11: Wireless local networking — Ethernet without the cable, plus encryption and airtime management.

BT: Short-range 2.4 GHz wireless with two protocol stacks: Classic BR/EDR for streaming audio, and BLE for low-power sensors, trackers, hearing aids, and IoT commissioning.

4G / 5G: The 3GPP radio family that gets a phone an IP address from a base station 50 km away — every modern smartphone, every IoT cellular module, ~9 billion subscriptions, the largest wireless deployment on Earth.

NFC: 13.56 MHz inductively-coupled short-range (≤10 cm) protocol family for payments, transit, identity, access, and tap-to-pair commissioning.

ZB: IEEE 802.15.4-based low-power mesh networking — the radio under every Philips Hue bulb, IKEA Trådfri light, and Walmart shelf label on Earth.

UWB: Sub-nanosecond impulse-radio at 6–9 GHz that measures time-of-flight to 10–30 cm — AirTag Precision Finding, BMW Digital Key, and Aliro hands-free unlock all ride this.