What Is GitHub Actions? CI/CD Built Into GitHub, Explained

GitHub Actions is GitHub's built-in automation platform. It runs workflows defined in YAML whenever something happens in your repository.

GitHub Actions lets you automate building, testing, and deploying code without leaving GitHub. You describe what should happen in YAML files, and GitHub runs that work on virtual machines called runners whenever a matching event occurs.

What it is

GitHub Actions is a continuous integration and continuous delivery (CI/CD) service hosted inside GitHub. Instead of wiring up a separate CI server, you commit workflow files to your repo and GitHub executes them automatically.

How it works

You place YAML files under .github/workflows/. Each file declares one or more events to listen for and the jobs to run when they fire. GitHub provisions a runner, checks out your code, executes the steps, and reports status back to the commit or pull request.

A minimal workflow

name: CI
on: [push]
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm ci && npm test

The core building blocks

Workflow: the YAML file that ties events to jobs.
Job: a set of steps that runs on one runner.
Step: a single command or action.
Action: a reusable, packaged unit of work.

Why it matters

Because it lives next to your code, GitHub Actions makes automation a first-class part of every pull request. Status checks, deploys, and security scans all run the moment code changes, giving fast feedback with no separate tooling to maintain.

Where it runs

Workflows run on GitHub-hosted runners by default, but they can also run on self-hosted or managed runners. Latchkey runs these same workflows on managed runners that are cheaper than GitHub-hosted and self-healing when an instance fails.

Key takeaways

GitHub Actions is GitHub's native CI/CD platform.
Workflows are YAML files in .github/workflows/ triggered by events.
The model is events to workflows to jobs to steps.