Glossary

Common coding terms Matt-splained.

2

200 OK: The request succeeded.

4

404 Not Found: The server can’t find the requested resource.

5

500 Internal Server Error: The server had an unexpected problem.

A

A/B test: Show different versions to users to see which performs better.
Accessibility: Design and code so everyone can use your site, including people with disabilities.
Alt text: Text that describes an image for screen readers and slow connections.
API key: A secret value used to authenticate a program to an API.
Argument: The actual value you pass into a function’s parameter.
Array / List: An ordered collection of values.
Astro: A web framework that ships minimal JavaScript by default.

B

Back-end: Behind-the-scenes logic: Data crunching, user authentication, payment processing.
Boolean: A value that’s either true or false.
Branch: A separate line of work for changes.
Bug: An error that makes software behave unexpectedly.
Build: Process that prepares code for production (bundling, minifying, etc.).
Bundler: Tool that combines many files into a few optimized ones.

C

Cache: Stored results to avoid doing the same work again.
CDN: Servers around the world that serve your static files quickly.
CI/CD: Automation that tests and ships code on every change.
Class: A template for creating objects with the same shape/behavior.
CLI: A command line interface (CLI), also known as a "terminal", is a text‑based interface to run commands.
Client: The device/app that requests and uses data from a server.
Clone: Make a local copy of a remote repo.
Commit: A saved snapshot of your changes with a message.
Component: A self‑contained, reusable piece of UI.
Conditional (if/else): Run code only when a condition is met.
Constant: Like a variable, but its value cannot change after it’s set.
Cookie: Small data saved by a website in your browser.
CORS: Rules that control which websites can talk to your server.
CSR (Client‑Side Rendering): The browser renders the page from data using JavaScript.
CSRF: An attack that tricks a logged‑in user into making a request they didn’t intend.
CSS: The visual styling (layout, colors, fonts).

D

Database: A structured place to store and query data.
Debugging: Finding and fixing bugs.
Dependency: Another package or library your project relies on.
Deploy: Putting your app or site live for users.
DNS: Service that turns names (example.com) into IP addresses.
DOM: The in‑memory structure of a web page that JS can change.

E

E2E: Short for "End-to-end". Tests the entire app like a real user would.
Endpoint: A specific URL where an API resource lives.
Environment variable (.env): Configuration values (often secrets) set outside your code.
Expression: Code that produces a value.

F

Feature flag: A switch that turns features on/off without redeploying.
Fork: Copy someone else’s repo to your own account to experiment.
Framework: A structured foundation that provides patterns and tools to build apps.
Front-end: Everything users interact with directly on your website or app (i.e. buttons, text, slick animations).
Full‑stack: Working on both frontend and backend.
Function: Reusable code that does a task, often returns a result.

G

Git: The most common version control system.
Glue Code: Glue code refers to small bits of code written to connect different software components, libraries, systems, or APIs that were not originally designed to work together. It's not responsible for the co...
GraphQL: An API where clients ask for exactly the data they need.

H

Hosting: Paying a company to keep your website’s files on a server connected to the internet.
HTML: The structure and content of web pages.
HTTP / HTTPS: The protocol for moving data on the web; HTTPS is the secure version.
Hydration: Activating static HTML with JavaScript so it becomes interactive.

I

IDE: Integrated Development Environment. An all‑in‑one code editor with helpful tools.
Index: A data structure that speeds up lookups.
Integration test: Tests how pieces of the system work together.
IP address: A numeric address for a device on a network.
Islands architecture: Mostly static pages with small interactive sections (“islands”).

J

JavaScript: The language that makes web pages interactive.
JSON: A lightweight text format for sending data.
JWT: Stands for "JSON Web Tokens", a signed token proving your identity that servers can verify.

L

Latency: How long it takes for a response to start arriving.
Library: Reusable code you can call in your project.
Local storage: Key–value storage inside the browser.
Loop: Repeat a block of code while a condition is true or for each item.

M

Markdown: Plain text with simple symbols for formatting.
Merge: Combine changes from one branch into another.
Method: A function that belongs to an object or class.
Migration: A scripted change to your database structure or data.
Minification: Shrinking files by removing whitespace and short names.
Mock: A fake stand‑in for a real dependency used during tests.
Module: A single file or small bundle of related code.

N

Node.js: Runs JavaScript outside the browser (on servers or your machine).
NoSQL: Databases that aren’t strictly tables/rows (e.g., documents, key‑value).
npm: JavaScript’s package manager for installing libraries.
Null / Undefined: A special value meaning “nothing here” or “not set.”
Number (int/float): Numeric data, whole or with decimals.

O

OAuth: A way to log in via another service without sharing your password.
Object / Dictionary: A collection of key–value pairs.
Operator: Symbols that do math or comparisons (+, -, >, &&, etc.).

P

Package: A shareable bundle of code (often a library + metadata).
package.json: Project file that lists dependencies and scripts.
Parameter: The placeholder name inside a function for an input value.
Props (properties): Inputs passed into a component.
Pull Request (PR): A request to review and merge your code into the main code.

R

Rate limit: A cap on how often you can call an API.
React: A popular library for building UI (user interface) with components and state.
README: A guide in the repo that explains how to use or develop the project.
Refactor: Improve the code’s structure without changing what it does.
Repository (repo): A project folder tracked by Git, including its history.
Responsive design: Layouts that adapt to different screen sizes.
REST API: A common style of web APIs using URLs and HTTP verbs.
Runtime: The period when your code is actually executing.

S

Schema: The structure that defines how data is organized.
Semantic HTML: Using correct tags that describe meaning (e.g., <nav>, <main>).
Server: A computer that’s always on, ready to respond to requests from other computers (a.k.a. clients).
Shell: The language/environment your terminal uses (e.g., bash, zsh).
SPA (Single‑Page App): A web app that loads once and updates views without full page reloads.
SQL: A language for querying and managing relational databases.
SSG (Static Site Generation): Pages are prebuilt as static files at build time.
SSR (Server‑Side Rendering): Pages are rendered on the server and sent ready to view.
Stack trace: A report showing which functions were running when an error happened.
State: The current data that drives what a component shows.
Statement: A complete instruction that does something.
String: Text data.

T

Technical debt: Shortcuts that speed you up now but cost more later.
Tree shaking: Removing unused code during the build.

U

Unit test: Tests a small piece of code in isolation.
Uptime: How much of the time a service is available.
URL: The address of a page or resource on the web.

V

Variable: A named container that holds a value you can change.
Version control: Tracks changes to files over time with history and branches.

W

Webhook: A URL you give a service so it can notify your app when something happens.

X

XSS: Stands for "Cross-Site Scripting". An attack where untrusted scripts run in your page.