# RFC Explained

> RFC Explained turns IETF RFCs into plain English: a TL;DR, the problem each
> standard solves, its status (current or obsoleted) and the parts people get wrong.

Every page is also served as clean Markdown at the same URL with a `.md` suffix.
Each explainer exists in English under `/en/` and in German under `/de/` with an
identical structure; the English version is canonical. English pages are listed
below by theme, the German translations follow in their own section.

## Concepts
- [What is an RFC?](https://rfc-explained.com/en/what-is-an-rfc.md): An RFC is a numbered IETF document that defines how a piece of the internet works. What Request for Comments means, who writes them, how the status system works, and how to read one.
- [The networking basics, explained](https://rfc-explained.com/en/networking-rfcs.md): The seven RFCs under every network: IPv4 addresses, the private and shared ranges, TCP and UDP, and the requirements document that made independent stacks interoperate.
- [The email RFCs, explained](https://rfc-explained.com/en/email-rfcs.md): The four RFCs behind email: RFC 5322 defines the message, RFC 5321 (SMTP) delivers it, and RFC 822 and 2822 are where the format came from. A guided map.
- [The network operations RFCs, explained](https://rfc-explained.com/en/network-ops-rfcs.md): The RFCs you meet running a network rather than building one: syslog in both dialects, RFC 5424 and the old 3164, plus RFC 2544 for measuring whether the box is fast enough.

## Networking basics
- [RFC 768: User Datagram Protocol](https://rfc-explained.com/en/768.md): UDP, the protocol that promises nothing.
- [RFC 791: Internet Protocol](https://rfc-explained.com/en/791.md): IPv4, the envelope every packet travels in.
- [RFC 793: Transmission Control Protocol](https://rfc-explained.com/en/793.md): TCP, the protocol that turns postcards into a phone call.
- [RFC 1122: Requirements for Internet Hosts - Communication Layers](https://rfc-explained.com/en/1122.md): Ten years of TCP/IP bug reports, written down.
- [RFC 1123: Requirements for Internet Hosts - Application and Support](https://rfc-explained.com/en/1123.md): The RFC that let hostnames start with a digit.
- [RFC 1918: Address Allocation for Private Internets](https://rfc-explained.com/en/1918.md): Private IP addresses, explained like you're new here.
- [RFC 6598: IANA-Reserved IPv4 Prefix for Shared Address Space](https://rfc-explained.com/en/6598.md): The fourth private range nobody voted for.

## Formats & encoding
- [RFC 3339: Date and Time on the Internet: Timestamps](https://rfc-explained.com/en/3339.md): The timestamp format you google ten times a week.

## OAuth & identity
- [RFC 6749: The OAuth 2.0 Authorization Framework](https://rfc-explained.com/en/6749.md): How apps get access without getting your password.

## Email
- [RFC 822: Standard for the Format of ARPA Internet Text Messages](https://rfc-explained.com/en/822.md): The shape of every email, defined in 1982.
- [RFC 2822: Internet Message Format](https://rfc-explained.com/en/2822.md): The email format's in-between edition.
- [RFC 5321: Simple Mail Transfer Protocol](https://rfc-explained.com/en/5321.md): The protocol that actually delivers your email.
- [RFC 5322: Internet Message Format](https://rfc-explained.com/en/5322.md): The anatomy of an email, and why the From line can lie.

## Ops & infrastructure
- [RFC 2544: Benchmarking Methodology for Network Interconnect Devices](https://rfc-explained.com/en/2544.md): The MOT test for network boxes, explained.
- [RFC 3164: The BSD syslog Protocol](https://rfc-explained.com/en/3164.md): The syslog format that was never really a standard.
- [RFC 5424: The Syslog Protocol](https://rfc-explained.com/en/5424.md): Syslog, with a real timestamp at last.

## HTTP
- [RFC 9110: HTTP Semantics](https://rfc-explained.com/en/9110.md): What HTTP means, no matter how it travels.

## Standards & meta
- [RFC 2119: Key words for use in RFCs to Indicate Requirement Levels](https://rfc-explained.com/en/2119.md): MUST, SHOULD and MAY, defined once and for all.

## German translations
The same explainers in German, one `.md` page per RFC under `/de/`, structurally
identical to their English counterparts.
- [Was ist ein RFC? (concept)](https://rfc-explained.com/de/was-ist-ein-rfc.md)
- [Die Netzwerk-Grundlagen, erklärt (cluster)](https://rfc-explained.com/de/netzwerk-rfcs.md)
- [Die E-Mail-RFCs, erklärt (cluster)](https://rfc-explained.com/de/email-rfcs.md)
- [Die Betriebs-RFCs fürs Netzwerk, erklärt (cluster)](https://rfc-explained.com/de/netzwerk-betrieb-rfcs.md)
- [Index of all German RFC explainers](https://rfc-explained.com/de/)
- [RFC 768: User Datagram Protocol](https://rfc-explained.com/de/768.md): UDP, das Protokoll, das nichts verspricht.
- [RFC 791: Internet Protocol](https://rfc-explained.com/de/791.md): IPv4, der Umschlag, in dem jedes Paket reist.
- [RFC 793: Transmission Control Protocol](https://rfc-explained.com/de/793.md): TCP, das Protokoll, das aus Postkarten einen Telefonanruf macht.
- [RFC 822: Standard for the Format of ARPA Internet Text Messages](https://rfc-explained.com/de/822.md): Die Gestalt jeder E-Mail, festgelegt 1982.
- [RFC 1122: Requirements for Internet Hosts - Communication Layers](https://rfc-explained.com/de/1122.md): Zehn Jahre TCP/IP-Fehlerberichte, aufgeschrieben.
- [RFC 1123: Requirements for Internet Hosts - Application and Support](https://rfc-explained.com/de/1123.md): Der RFC, der Hostnamen mit führender Ziffer erlaubte.
- [RFC 1918: Address Allocation for Private Internets](https://rfc-explained.com/de/1918.md): Private IP-Adressen, erklärt als wärst du neu hier.
- [RFC 2119: Key words for use in RFCs to Indicate Requirement Levels](https://rfc-explained.com/de/2119.md): MUST, SHOULD und MAY, ein für alle Mal definiert.
- [RFC 2544: Benchmarking Methodology for Network Interconnect Devices](https://rfc-explained.com/de/2544.md): Der TÜV für Netzwerk-Hardware, erklärt.
- [RFC 2822: Internet Message Format](https://rfc-explained.com/de/2822.md): Die Zwischenausgabe des E-Mail-Formats.
- [RFC 3164: The BSD syslog Protocol](https://rfc-explained.com/de/3164.md): Das Syslog-Format, das nie wirklich ein Standard war.
- [RFC 3339: Date and Time on the Internet: Timestamps](https://rfc-explained.com/de/3339.md): Das Timestamp-Format, das du zehnmal pro Woche googelst.
- [RFC 5321: Simple Mail Transfer Protocol](https://rfc-explained.com/de/5321.md): Das Protokoll, das deine E-Mail wirklich zustellt.
- [RFC 5322: Internet Message Format](https://rfc-explained.com/de/5322.md): Die Anatomie einer E-Mail, und warum die From-Zeile lügen kann.
- [RFC 5424: The Syslog Protocol](https://rfc-explained.com/de/5424.md): Syslog, endlich mit echtem Zeitstempel.
- [RFC 6598: IANA-Reserved IPv4 Prefix for Shared Address Space](https://rfc-explained.com/de/6598.md): Der vierte private Bereich, den niemand gewählt hat.
- [RFC 6749: The OAuth 2.0 Authorization Framework](https://rfc-explained.com/de/6749.md): Wie Apps Zugriff bekommen, ohne dein Passwort zu bekommen.
- [RFC 9110: HTTP Semantics](https://rfc-explained.com/de/9110.md): Was HTTP bedeutet, egal wie es reist.

## Optional
- [Index of all RFC explainers (English)](https://rfc-explained.com/en/)