Reference

Short, plain-language reference pages for the concepts the course leans on but doesn’t slow down to explain from scratch. Read them when a term shows up that you’d like grounded properly — no prior backend knowledge assumed.

Pages

• What is an API? — clients, servers, REST, endpoints, and JSON, explained for testers.
• HTTP fundamentals — the anatomy of a request and a response: methods, URLs, headers, and bodies.
• HTTP status codes — what 200, 201, 400, 401, 404, 500 and the rest actually mean, with a full reference table.
• CSS selectors — elements, classes, ids, attributes, combinators, and the selector engines Playwright layers on top.
• Regular expressions — literals, anchors, character classes, quantifiers, groups, and flags, grounded in the course’s real toHaveURL(/…/) patterns.
• Git & GitHub basics — repositories, the staging area, commits, branches, remotes, pull requests, and .gitignore, using the commands the course already runs.
• DOM & HTML basics — tags, attributes, the element tree, id vs class, and the semantic elements and roles behind getByRole and accessibility testing.
• Cookies & sessions — how a browser stays logged in, what HttpOnly means, and how it connects to storageState.
• Accessibility, ARIA & WCAG — the POUR principles, ARIA attributes, and the violations axe-core catches.
• Command line & npm — the terminal, Node, package.json, npm install, and npx — the commands the course runs.
• SQL basics — SELECT, WHERE, JOIN, aggregates, and parameterized queries for reading a test database, grounded in TestMarket Lab’s real schema.
• Docker basics — installing Docker, images, containers, docker run, ports and env vars, Compose, and the GitHub Actions service container — how to spin up a real database for your tests.

Where this fits

Each page backs up the module that leans on it hardest:

• Command line & npm → Module 0 — setup.
• CSS selectors and DOM & HTML → Module 2 — Locators.
• Regular expressions → the assertion modules (Module 4 and around it).
• APIs / HTTP / status codes → Module 9 — API testing & networking.
• Cookies & sessions → Module 10 — Authentication.
• Accessibility, ARIA & WCAG → Module 11 — accessibility testing.
• Git & GitHub → Module 12 — CI, Docker, reports.
• SQL basics → Database verification in the Python SDET course (live), and the Playwright course’s DB module (coming).
• Docker basics → those same Database verification modules and Module 12 — CI, Docker, reports.

Read them whenever a term shows up that you’d like grounded properly — no prior backend or front-end knowledge assumed.