How do GitHub Actions workflows work?

Workflows live in .github/workflows and are triggered by events such as push, pull_request or a manual dispatch. Jobs run in parallel by default unless you declare dependencies with needs.

• Use on to define events and paths that trigger the workflow
• Use jobs and steps to structure work; steps in a job share a workspace
• Use needs to express dependencies and pass outputs between jobs
• Use a matrix to run the same job across versions or platforms
• Set explicit permissions and pin third-party actions to a SHA
• Use environments and required reviewers for protected deployments

name: ci
on:
  pull_request:
  push:
    branches: [main]

permissions:
  contents: read

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@<pinned-sha>
      - uses: actions/setup-node@<pinned-sha>
        with:
          node-version: 22
          cache: npm
      - run: npm ci
      - run: npm test