Glossary
What the words on this site mean — one line each, a full article for some, and a link to the people who define them.
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. Where the site has written a longer article about a word, the name opens the article instead, and its further reading starts at that same source.
- access control
- granting or refusing each request to use a resource
- accessibility
- a site's fitness for people with disabilities
- ACME
- the protocol that issues a certificate without a human
- alert
- a message a system sends when something needs a person
- animation
- a change in a page's look played out over time
- Ansible
- a tool that puts a server into a written-down state
- API
- the described way one program calls another
- app
- a program people use to get a task done
- ArcGIS
- Esri's commercial GIS platform
- architecture
- how a system's parts fit together and why
- ARIA
- extra markup that names a control for assistive tech
- authentication
- proof that a request is from who it claims
- AWS
- Amazon's cloud platform
- axe
- the accessibility engine this site is audited with
- Azure
- Microsoft's cloud platform
- backend
- the half of a system the reader never loads
- backup
- a copy of data against loss, and the making of it
- Bash
- the GNU shell most scripts are written for
- Bicep
- Azure's own language for declaring infrastructure
- BigQuery
- Google's warehouse for querying very large tables
- button
- a control a person presses to make something happen
- cache
- a stored copy a browser may reuse instead of asking
- caching
- keeping an answer so the work is not repeated
- canonical URL
- the one address a page says is its own
- CDN
- servers near the reader that hand out copies
- CI
- merging work at least daily, each merge proven by a build
- cloud
- computing rented by the hour from somebody else
- codebase
- all the source code of one app, kept in one repository
- computer file
- a named set of data stored as one unit
- configuration
- the settings that decide how a system behaves
- container runtime
- the program that actually starts a container
- Content Security Policy
- a list of where a page may load things from
- contrast ratio
- how far apart two colours are, as a number
- cookie
- a small value a site asks the browser to keep
- Core Web Vitals
- three measurements of how a page feels to use
- crawler
- a program that fetches pages to index them
- CSS
- the language that says how a page looks
- CTE
- a named subquery a bigger query reads as a table
- daemon
- a program that runs in the background, unattended
- dashboard
- one screen built to answer a recurring question
- data storage
- keeping data, or the media that hold it, for later reading
- database
- a store of data organised so that programs can query it
- dataset
- a collection of data published as one unit
- defect
- a flaw that keeps a product from meeting its requirements
- deployment
- moving a change to where people actually use it
- DevOps
- practices that join software development and operations
- Django
- a Python framework for building web applications
- DNS
- the directory turning a name into an address
- Docker
- a way to ship a program with everything it needs
- downtime
- the stretch where a service answers nobody
- mail sent between mailboxes across the internet
- encryption
- making data unreadable without the key
- ESLint
- a rule-driven linter for JavaScript
- ETL
- moving data between systems, reshaping it on the way
- favicon
- the small picture a browser shows beside a page
- feed
- a page's updates, in a format you subscribe to
- firewall
- the rule set that decides which traffic passes
- font
- a typeface in a file the page downloads
- forge
- a web platform where code is hosted, reviewed and shared
- frontend
- the half of a system that runs in the reader's browser
- GDAL
- the library that reads every geospatial format
- Gemini
- a lightweight internet protocol for serving hypertext
- gemtext
- a text format with one link per line
- GeoJSON
- geography written as JSON
- geospatial
- data whose meaning depends on where it is
- GIS
- systems for data that has a place on a map
- git
- the version control this site's history lives in
- git hook
- a script git runs when something happens
- GitHub
- Microsoft's hosting for git repositories
- GitLab
- a git platform you can also run yourself
- Go
- a compiled, strongly typed, garbage-collected language
- Google Cloud
- Google's cloud platform
- Gopher
- a menu protocol older than the web
- Grafana
- a dashboard tool for metrics and logs
- hardening
- removing what an attacker could use
- hardware
- the physical parts of a computer
- host
- a computer attached to a network
- hreflang
- the attribute pairing a page with its translations
- HSTS
- a browser's promise to use HTTPS next time
- HTML
- the language a page's structure is written in
- HTTP
- the request and answer the web is built on
- HTTPS
- the same requests, over an encrypted connection
- idempotent
- safe to run twice, because the second time changes nothing
- incident
- an event that puts a system's data or service at risk
- information security
- protecting data and systems from misuse and harm
- JavaScript
- the language browsers run
- JSON
- the text format most data travels in
- kernel
- the core of an operating system
- Kubernetes
- a system that keeps a fleet of containers running
- landmark
- a region of a page a screen reader can jump to
- latency
- the wait between asking and the first of the answer
- Leaflet
- a small library for maps in a browser
- library
- code packaged for other programs to call
- Lighthouse
- Chrome's own audit of speed, markup and good practice
- linter
- a tool that flags likely bugs in code without running it
- Linux
- the kernel most servers run on
- logging
- writing down what happens, as it happens
- macOS
- Apple's desktop operating system
- Mapbox
- a commercial source of map tiles and styles
- Markdown
- plain text with a few marks that mean formatting
- metadata
- the data describing other data, so it can be found
- metrics
- numbers a system reports about itself
- monitoring
- watching a running system so it tells you first
- network server
- a computer or program that serves others over a network
- Next.js
- a React framework for building web apps
- nginx
- a web server and reverse proxy
- onion service
- an address that works only through Tor
- OpenAPI
- a machine-readable description of an HTTP API
- OpenTelemetry
- one vendor-free way to send telemetry
- operating system
- the software that manages hardware for every other program
- operational secret
- a credential a program needs, like a key or a password
- package
- code bundled with a description, ready to install
- partitioning
- splitting one table into physical pieces
- password
- a secret string that proves who is signing in
- PHP
- the language most of the old web runs on
- pipeline
- a run of steps carrying data from source to use
- Playwright
- the tool that drives a browser in tests
- Podman
- a container engine that needs no daemon
- port
- the number that picks a service on a host
- PostGIS
- the extension that gives PostgreSQL geometry
- PostgreSQL
- the database most of this work was built on
- privilege
- a right a system grants to a person or process
- Prometheus
- a database that scrapes and stores metrics
- protocol
- the agreed rules two programs follow to talk
- proxy
- a server that forwards a request on your behalf
- Python
- the language most of this site's tooling is in
- QGIS
- the free desktop GIS
- quality gate
- a set of checks code must pass before it moves on
- query
- a written question a database answers
- queue
- work left in order for something else to pick up
- RBAC
- permissions granted to a role, not a person
- Redis
- an in-memory store for things that live briefly
- repository
- a store that keeps saved versions of a set of files
- robots.txt
- the file telling crawlers where not to go
- RSS
- the older of the two XML formats a feed is written in
- Ruff
- a fast linter and formatter for Python
- Rust
- a compiled language that checks memory for you
- scalability
- whether more load needs more than more machines
- schema
- a named group of tables inside one database
- screen reader
- software that reads a page aloud, or into braille
- SEO
- making a page findable without paying for it
- service worker
- a script that answers requests when the network cannot
- sitemap
- a list of a site's pages, written for machines
- software
- the programs and data a computer runs
- SQL
- the language relational databases answer
- SQL Server
- Microsoft's relational database
- SQLite
- a whole database in a single file
- SSH
- an encrypted shell on another machine
- static site generator
- a program that writes every page out in advance
- structured data
- facts about a page, written for machines
- stylesheet
- the file that holds a page's CSS
- Subresource Integrity
- a hash a browser checks a file against
- systemd
- the thing that starts everything else on Linux
- TLS
- the handshake that encrypts a connection
- Tor
- a network that routes traffic through volunteer relays
- TypeScript
- JavaScript with types checked before it runs
- Ubuntu
- a Linux distribution common on servers
- UI
- the part of a program a person sees and works with
- URL
- the address that says where a thing is
- user
- a person, or a process acting for one, allowed into a system
- validation
- checking input against the rules before trusting it
- viewport
- the part of a page a window actually shows
- VPN
- a private network carried over a public one
- WCAG 2.2
- the accessibility standard this site is held to
- web app manifest
- the file that lets a site be installed
- web browser
- the program a person uses to open web pages
- WebP
- an image format smaller than the ones it replaces
- website
- a set of related web pages under one address
- WordPress
- the CMS most of the web is published with
- YAML
- a format for settings a person can still read
