Astro glossary

Every term a beginner runs into, explained in plain English.

A

Adapter: A small add-on that lets Astro run server code on a particular host.
AGENTS.md: A file in your project that gives AI coding tools instructions about how it works.
Antigravity: Google's coding agent for the terminal. Its command is agy. It replaced the Gemini CLI for personal use in June 2026.
astro add: A command that installs an integration and sets it up for you.
Astro component: A reusable building block of a page, saved in a file ending in .astro.
Astro config: The file named astro.config.mjs, where you set options for your project.

B

Browser: The program you use to look at websites, like Chrome, Safari, Edge or Firefox.
Build: The step that turns your project into a finished website.

C

Canonical URL: A tag that tells search engines a page's one true address.
CDN: A network of servers around the world that delivers your site from somewhere close to each visitor.
ChatGPT: OpenAI's AI assistant, available as a chat and, through Codex, as a coding agent.
Claude: Anthropic's AI assistant, available as a chat at claude.ai and as the Claude Code coding tool.
Claude Code: Anthropic's coding tool that reads your project, edits files and runs commands with your approval.
Client directive: An attribute like client:load that turns a component into an island and says when its JavaScript should load.
Cloudflare Workers: Cloudflare's hosting platform, which can serve a static Astro site or run server code.
CMS: A website-style editor that lets people change content without touching code.
Codex: OpenAI's coding agent, which edits your project and runs commands like Claude Code does.
Content collection: A group of related content, such as blog posts, that Astro loads and checks for you.
Core Web Vitals: Google's measurements of how fast and stable a page feels to real visitors.
CSS: The code that says how a page looks: colours, sizes, spacing and fonts.
Cursor: A code editor built around AI assistance, based on VS Code.

D

D1: Cloudflare's database. EmDash keeps your posts, pages, users and settings in it.
DeepSeek: A Chinese AI lab whose chat, at chat.deepseek.com, can write Astro code for you to paste in.
Deploy: To publish your site so that anyone can visit it.
Dev server: A private preview of your site that updates as you edit.
dist folder: The folder where Astro puts your finished website.
Domain name: A website's address, like astronursery.com. You rent it by the year and point it at your host.
Dynamic route: One page file that creates many pages, with square brackets in its name.

E

EmDash: An open-source content management system from Cloudflare, built on Astro.

F

Framework component: A component written in React, Preact, Vue, Svelte or SolidJS and used inside an Astro page.
Frontmatter: The section at the top of a file, between two lines of three dashes.

G

Gemini: Google's AI assistant, with a free chat at gemini.google.com and a coding agent called Antigravity.
Giscus: A free comments tool that stores comments as GitHub Discussions.
Git: A tool that saves the history of your project so you can undo mistakes.
GitHub: A website that keeps a copy of your project online and remembers every change.
GitHub Copilot: An AI assistant that works inside VS Code and other editors.
Grok: xAI's AI assistant, at grok.com. Its coding agent, Grok Build, is an early beta for paid plans.

H

Hallucination: When an AI states something false with confidence, such as an Astro feature or setting that does not exist.
Headless CMS: A content system that stores and edits your content but leaves the display to your site.
Homebrew: A tool for the Mac that installs other tools, such as Node.js, with one line.
Honeypot: A hidden form field that people never fill in but bots do, so their submissions can be thrown away.
Hosting: The service that keeps your website online.
HTML: The language that describes what's on a web page.
Hydration: When JavaScript wakes up a piece of a page so that it becomes interactive.

I

Integration: An add-on that gives your Astro project a new ability. Astro's word for a plugin.
Islands: Interactive parts of a page, surrounded by plain static HTML.

J

JavaScript: The programming language that makes web pages interactive.

K

Kimi: Moonshot AI's assistant, at kimi.com, with a coding agent called Kimi Code CLI.

L

Layout: A component that wraps your pages with shared parts, such as a header and footer.
LLM: Large language model: the kind of AI behind Claude and ChatGPT.
llms.txt: A plain-text file at the root of a site that lists its pages for AI tools to read. A proposal, not a standard.
localhost: An address that means this computer.

M

Markdown: A simple way to write formatted text with ordinary characters.
MCP: Model Context Protocol: a standard way to give an AI tool access to outside information, such as live documentation.
MDX: Markdown that can also use components.
Meta description: The short summary of a page that search engines may show under its title.

N

Node.js: The program that runs Astro's tools on your computer.
npm: The tool that downloads and manages the code packages your project uses.

O

On-demand rendering: Creating a page when someone asks for it, rather than ahead of time.
Open Graph: Tags in a page that control how it looks when shared on social media or in chat apps.

P

package.json: The file that lists your project's tools and commands.
Pagefind: A free search tool for static sites. It builds a search index as files at build time, and the browser does the searching.
Passkey: A way to log in without a password, using your device and fingerprint or face.
Prompt: The message you give an AI tool. A good one states your situation, one job, and your version numbers.
Props: Values you pass into a component, like filling in a form.

Q

Qwen Code: An open-source coding agent from Alibaba's Qwen team, run with the qwen command.

R

R2: Cloudflare's file storage. EmDash keeps your uploaded images and files in it.
Redirect (301): A rule that sends one address to another. A 301 means "moved for good", and search engines pass the ranking along.
Registrar: A company that rents you a domain name, a year at a time.
Routing: How addresses on your site map to pages.
RSS: A feed of your latest posts that people can follow in a reader app.

S

Schema: A checklist that says what each piece of content must include.
SEO: Search engine optimization: the work of helping a site show up in search results.
Server island: A part of a page that's rendered on the server when someone visits, while the rest of the page was built ahead of time.
Sitemap: A file that lists every page on your site for search engines.
Slot: A placeholder in a component where outside content goes.
Spacefast: A host from Automattic, the company behind WordPress.com. Our pick for most Astro sites.
Starlight: The Astro team's free theme for documentation sites.
Static site: A website whose pages are finished before anyone visits.
Structured data: A block of data in a page that describes its content to search engines.

T

Tailwind CSS: A way of styling pages with small, ready-made classes instead of writing CSS rules.
Terminal: A window where you control your computer by typing commands.
Theme: A ready-made Astro project with a finished design.
TypeScript: JavaScript with added type checking, which catches mistakes before your site builds.

V

Vibe coding: Building software by describing what you want to an AI and accepting the code without reading it closely.
View transitions: Smooth animations between one page and the next.
Vite: The build tool that runs underneath Astro.

W

Web analytics: A tool that counts your visitors and shows which pages they read. Google Analytics and Cloudflare Web Analytics are two.
WebP: A modern image format that makes files much smaller than JPEG or PNG.
Wrangler: Cloudflare's command-line tool for putting sites and apps on Cloudflare.
WXR file: The XML file WordPress produces when you export your content.