# Glossary This site explains itself in public. The credits name every piece of technology behind it, the notes argue about browser bugs, and the conformance claim cites clauses by number — so a reader who follows any of that meets words that are precise and unfamiliar at the same time. Each one below gets a line. The name links to the people who define it, because a summary is a place to start and a specification is the thing that is true. - [accessibility](https://www.w3.org/WAI/fundamentals/accessibility-intro/) — a site's fitness for people with disabilities - [ACME](https://www.rfc-editor.org/rfc/rfc8555) — the protocol that issues a certificate without a human - [Ansible](https://docs.ansible.com/ansible/latest/index.html) — a tool that puts a server into a written-down state - [ArcGIS](https://developers.arcgis.com/documentation/) — Esri's commercial GIS platform - [ARIA](https://www.w3.org/TR/wai-aria-1.2/) — extra markup that names a control for assistive tech - [authentication](https://pages.nist.gov/800-63-3/sp800-63b.html) — proof that a request is from who it claims - [AWS](https://docs.aws.amazon.com/) — Amazon's cloud platform - [axe](https://github.com/dequelabs/axe-core) — the accessibility engine this site is audited with - [Azure](https://learn.microsoft.com/en-us/azure/) — Microsoft's cloud platform - [backup](https://csrc.nist.gov/glossary/term/backup) — a copy of data against loss, and the making of it - [Bash](https://www.gnu.org/software/bash/manual/bash.html) — the GNU shell most scripts are written for - [Bicep](https://learn.microsoft.com/en-us/azure/azure-resource-manager/bicep/overview) — Azure's own language for declaring infrastructure - [BigQuery](https://cloud.google.com/bigquery/docs/introduction) — Google's warehouse for querying very large tables - [cache](https://www.rfc-editor.org/rfc/rfc9111) — a stored copy a browser may reuse instead of asking - [canonical URL](https://www.rfc-editor.org/rfc/rfc6596) — the one address a page says is its own - [CDN](https://www.rfc-editor.org/rfc/rfc6707#section-1.1) — servers near the reader that hand out copies - [cloud](https://csrc.nist.gov/pubs/sp/800/145/final) — computing rented by the hour from somebody else - [container runtime](https://github.com/opencontainers/runtime-spec) — the program that actually starts a container - [Content Security Policy](https://www.w3.org/TR/CSP3/) — a list of where a page may load things from - [contrast ratio](https://www.w3.org/TR/WCAG22/#dfn-contrast-ratio) — how far apart two colours are, as a number - [cookie](https://www.rfc-editor.org/rfc/rfc6265) — a small value a site asks the browser to keep - [Core Web Vitals](https://web.dev/articles/vitals) — three measurements of how a page feels to use - [crawler](https://www.rfc-editor.org/rfc/rfc9309) — a program that fetches pages to index them - [CSS](https://www.w3.org/TR/CSS/) — the language that says how a page looks - [CTE](https://www.postgresql.org/docs/current/queries-with.html) — a named subquery a bigger query reads as a table - [daemon](https://man7.org/linux/man-pages/man7/daemon.7.html) — a program that runs in the background, unattended - [Django](https://docs.djangoproject.com/en/stable/) — a Python framework for building web applications - [DNS](https://www.rfc-editor.org/rfc/rfc1035) — the directory turning a name into an address - [Docker](https://docs.docker.com/) — a way to ship a program with everything it needs - [encryption](https://csrc.nist.gov/glossary/term/encryption) — making data unreadable without the key - [ESLint](https://eslint.org/docs/latest/use/core-concepts/) — a rule-driven linter for JavaScript - [favicon](https://html.spec.whatwg.org/multipage/links.html#rel-icon) — the small picture a browser shows beside a page - [feed](https://www.rfc-editor.org/rfc/rfc4287) — a page's updates, in a format you subscribe to - [firewall](https://csrc.nist.gov/glossary/term/firewall) — the rule set that decides which traffic passes - [font](https://www.w3.org/TR/css-fonts-4/) — a typeface in a file the page downloads - [GDAL](https://gdal.org/en/stable/) — the library that reads every geospatial format - [gemtext](https://geminiprotocol.net/docs/gemtext.gmi) — a text format with one link per line - [GeoJSON](https://www.rfc-editor.org/rfc/rfc7946) — geography written as JSON - [GIS](https://docs.qgis.org/latest/en/docs/gentle_gis_introduction/) — systems for data that has a place on a map - [git](https://git-scm.com/doc) — the version control this site's history lives in - [git hook](https://git-scm.com/docs/githooks) — a script git runs when something happens - [GitHub](https://docs.github.com/) — Microsoft's hosting for git repositories - [GitLab](https://docs.gitlab.com/) — a git platform you can also run yourself - [Google Cloud](https://cloud.google.com/docs) — Google's cloud platform - [Gopher](https://www.rfc-editor.org/rfc/rfc1436) — a menu protocol older than the web - [Grafana](https://grafana.com/docs/grafana/latest/introduction/) — a dashboard tool for metrics and logs - [hardening](https://csrc.nist.gov/glossary/term/hardening) — removing what an attacker could use - [hreflang](https://html.spec.whatwg.org/multipage/links.html#attr-hyperlink-hreflang) — the attribute pairing a page with its translations - [HSTS](https://www.rfc-editor.org/rfc/rfc6797) — a browser's promise to use HTTPS next time - [HTML](https://html.spec.whatwg.org/multipage/) — the language a page's structure is written in - [HTTP](https://www.rfc-editor.org/rfc/rfc9110) — the request and answer the web is built on - [HTTPS](https://www.rfc-editor.org/rfc/rfc9110#name-https-uri-scheme) — the same requests, over an encrypted connection - [idempotent](https://www.rfc-editor.org/rfc/rfc9110#name-idempotent-methods) — safe to run twice, because the second time changes nothing - [JavaScript](https://tc39.es/ecma262/) — the language browsers run - [JSON](https://www.rfc-editor.org/rfc/rfc8259) — the text format most data travels in - [kernel](https://docs.kernel.org/admin-guide/index.html) — the core of an operating system - [Kubernetes](https://kubernetes.io/docs/concepts/overview/) — a system that keeps a fleet of containers running - [landmark](https://www.w3.org/TR/wai-aria-1.2/#landmark_roles) — a region of a page a screen reader can jump to - [Leaflet](https://leafletjs.com/) — a small library for maps in a browser - [Lighthouse](https://developer.chrome.com/docs/lighthouse/overview) — Chrome's own audit of speed, markup and good practice - [Linux](https://www.kernel.org/linux.html) — the kernel most servers run on - [logging](https://opentelemetry.io/docs/concepts/signals/logs/) — writing down what happens, as it happens - [macOS](https://support.apple.com/guide/mac-help/welcome/mac) — Apple's desktop operating system - [Mapbox](https://docs.mapbox.com/help/getting-started/) — a commercial source of map tiles and styles - [Markdown](https://spec.commonmark.org/) — plain text with a few marks that mean formatting - [metrics](https://opentelemetry.io/docs/concepts/signals/metrics/) — numbers a system reports about itself - [nginx](https://nginx.org/en/docs/) — a web server and reverse proxy - [onion service](https://spec.torproject.org/rend-spec/) — an address that works only through Tor - [OpenAPI](https://spec.openapis.org/oas/latest.html) — a machine-readable description of an HTTP API - [OpenTelemetry](https://opentelemetry.io/docs/what-is-opentelemetry/) — one vendor-free way to send telemetry - [partitioning](https://www.postgresql.org/docs/current/ddl-partitioning.html) — splitting one table into physical pieces - [PHP](https://www.php.net/manual/en/introduction.php) — the language most of the old web runs on - [Playwright](https://playwright.dev/docs/intro) — the tool that drives a browser in tests - [Podman](https://docs.podman.io/en/latest/) — a container engine that needs no daemon - [port](https://www.rfc-editor.org/rfc/rfc9293#section-4) — the number that picks a service on a host - [PostGIS](https://postgis.net/documentation/) — the extension that gives PostgreSQL geometry - [PostgreSQL](https://www.postgresql.org/docs/current/intro-whatis.html) — the database most of this work was built on - [Prometheus](https://prometheus.io/docs/introduction/overview/) — a database that scrapes and stores metrics - [proxy](https://www.rfc-editor.org/rfc/rfc9110#section-3.7) — a server that forwards a request on your behalf - [Python](https://docs.python.org/3/) — the language most of this site's tooling is in - [QGIS](https://docs.qgis.org/latest/en/docs/user_manual/preamble/foreword.html) — the free desktop GIS - [RBAC](https://csrc.nist.gov/projects/role-based-access-control) — permissions granted to a role, not a person - [Redis](https://redis.io/docs/latest/develop/) — an in-memory store for things that live briefly - [robots.txt](https://www.rfc-editor.org/rfc/rfc9309) — the file telling crawlers where not to go - [RSS](https://www.rssboard.org/rss-specification) — one of the two formats a feed is written in - [Ruff](https://docs.astral.sh/ruff/) — a fast linter and formatter for Python - [Rust](https://doc.rust-lang.org/book/) — a compiled language that checks memory for you - [schema](https://www.postgresql.org/docs/current/ddl-schemas.html) — a named group of tables inside one database - [screen reader](https://www.w3.org/WAI/people-use-web/tools-techniques/) — software that reads a page aloud, or into braille - [SEO](https://developers.google.com/search/docs/fundamentals/seo-starter-guide) — making a page findable without paying for it - [service worker](https://www.w3.org/TR/service-workers/) — a script that answers requests when the network cannot - [sitemap](https://www.sitemaps.org/protocol.html) — a list of a site's pages, written for machines - [SQL](https://www.postgresql.org/docs/current/sql.html) — the language relational databases answer - [SQLite](https://sqlite.org/about.html) — a whole database in a single file - [SSH](https://www.rfc-editor.org/rfc/rfc4251) — an encrypted shell on another machine - [static site generator](https://gohugo.io/about/introduction/) — a program that writes every page out in advance - [structured data](https://schema.org/) — facts about a page, written for machines - [stylesheet](https://www.w3.org/TR/cssom-1/#css-style-sheet) — the file that holds a page's CSS - [Subresource Integrity](https://www.w3.org/TR/SRI/) — a hash a browser checks a file against - [systemd](https://man7.org/linux/man-pages/man1/systemd.1.html) — the thing that starts everything else on Linux - [TLS](https://www.rfc-editor.org/rfc/rfc8446) — the handshake that encrypts a connection - [Tor](https://spec.torproject.org/) — a network that routes traffic through volunteer relays - [TypeScript](https://www.typescriptlang.org/docs/) — JavaScript with types checked before it runs - [Ubuntu](https://ubuntu.com/server/docs) — a Linux distribution common on servers - [URL](https://www.rfc-editor.org/rfc/rfc3986) — the address that says where a thing is - [viewport](https://www.w3.org/TR/css-viewport-1/) — the part of a page a window actually shows - [VPN](https://www.rfc-editor.org/rfc/rfc4026#section-3.10) — a private network carried over a public one - [WCAG 2.2](https://www.w3.org/TR/WCAG22/) — the accessibility standard this site is held to - [web app manifest](https://www.w3.org/TR/appmanifest/) — the file that lets a site be installed - [WebP](https://developers.google.com/speed/webp) — an image format smaller than the ones it replaces - [WordPress](https://wordpress.org/documentation/) — the CMS most of the web is published with - [YAML](https://yaml.org/spec/1.2.2/) — a format for settings a person can still read