GitHub Actions
GitHub's built-in CI/CD platform that allows you to automate software workflows directly from your repository using YAML configuration files.
Definition
GitHub Actions uses YAML workflow files in .github/workflows/ to define automation. Workflows are triggered by events (push, pull_request, schedule, etc.) and run on GitHub-hosted or self-hosted runners. Key concepts: workflows (the automation), jobs (groups of steps), steps (individual commands), and actions (reusable units). The marketplace has thousands of community actions for testing, deployment, security scanning, and more.
Why It Matters
GitHub Actions has become the dominant CI/CD platform for open source and many enterprises. Its deep GitHub integration enables features like PR checks, automatic labeling, and issue automation. Free tier includes 2,000 minutes/month for private repos and unlimited minutes for public repos.
Example
A workflow that runs on every pull request: checks out code, installs dependencies, runs tests, runs linting, and posts coverage report as a PR comment. If any step fails, the PR cannot be merged.