Encyclopedia

64 web terms, explained simply

Every part of a website, grouped by layer. Each term has a plain-English definition, how it works and a real snippet.

Domain & network

How a name like example.com turns into a secure connection to a real machine.

URL: The full address of one resource on the web.
Domain name: The human-readable name for a site, like example.com.
Registrar: The company you rent a domain name from.
DNS: The internet's phone book. It turns names into IP addresses.
DNS records: The entries in a domain's phone-book listing.
IP address: The numeric address of a machine on the internet.
HTTP: The request–response language browsers and servers speak.
HTTPS & TLS: Encryption between the browser and the server. It's the padlock.

Where the files live and how they reach a visitor quickly.

Web server / host: A computer that answers HTTP requests with files or generated pages.
CDN: Copies of your site in data centers around the world.
Edge: Servers at the outer rim of the network, nearest the visitor.
Static site: Pages built ahead of time and served as plain files.
Dynamic site: Pages assembled on request, often from a database.
Caching: Reusing a saved copy instead of fetching or rebuilding it.
Serverless function: Server code that runs only when a request arrives.
Redirect: Sending a request from one URL to another.
Status codes: Three-digit codes that say how a request went.

Code and data that run on a server instead of in the visitor's browser.

API: A defined way for one program to ask another for data or actions.
Database: Where data that changes is stored and queried.
Authentication: Proving who a visitor is, and remembering it.
Environment variables & secrets: Configuration and keys kept outside the code.
Third-party services: Outside services you plug in instead of building.
Webhook: A service calling your URL when something happens.

The document itself: what each piece of content is.

How the document looks at every screen size.

What happens when someone clicks, types or scrolls.

Images, fonts, icons and files the page pulls in.

How search engines and AI systems find, read and describe the site.

Title tag: The clickable headline in search results and the browser tab.
Meta description: The gray summary under the result link.
Canonical URL: The one official address for a page.
Robots meta / noindex: A per-page instruction to keep a page out of search results.
robots.txt: A file at the site root that tells crawlers where not to go.
Sitemap: A list of every URL you want found.
Open Graph & social cards: Tags that control the preview when a link is shared.
Structured data (JSON-LD): Machine-readable facts about the page, in schema.org vocabulary.
Core Web Vitals: Google's three measures of how a page feels to use.
Internal links: Links between pages on your own site.
Backlinks: Links to your site from other sites.
Search Console: Google's dashboard for how it sees your site.
GEO (generative engine optimization): Being found, understood and cited by AI assistants.
llms.txt: A proposed Markdown summary of a site, written for language models.

Speed, accessibility, security and measurement, which every other layer depends on.

Performance: How fast the page loads and responds, especially on a phone.
Accessibility (a11y): Making the site usable by everyone, including people using assistive technology.
Security headers: Response headers that tell the browser to lock things down.
Analytics: Measuring who visits and what they do.
Lighthouse: Chrome's built-in audit for performance, accessibility, best practices and SEO.

How changes get from a laptop to the live site safely.

Git & GitHub: Version history for code, and a place to host it.
Branch: A parallel line of work.
CI/CD: Automatic checks and deploys on every push.
Preview deploy: A private, temporary copy of the site for each branch.
Static site generator: A tool that turns content and templates into HTML files.