Understanding workflows, events, jobs, and runners in GitHub Actions.
GitHub Actions is a powerful and flexible CI/CD platform built directly into GitHub. This tight integration makes it incredibly easy to get started with automation for projects hosted on the platform. The core concepts revolve around 'Workflows', which are defined in YAML files stored in the `.github/workflows` directory of your repository. A workflow is an automated process made up of one or more 'Jobs'. 'Events' are the triggers for these workflows; you can configure a workflow to run on a push to a branch, the creation of a pull request, a new issue being opened, or even on a schedule. Each job runs inside its own virtual machine or container, known as a 'Runner'. GitHub provides hosted runners for Linux, Windows, and macOS, but you can also host your own self-hosted runners for more control. A job is composed of a sequence of 'Steps'. A step can be a shell command or an 'Action'. Actions are a key feature; they are reusable units of code that can be shared and used across different workflows. The GitHub Marketplace has thousands of pre-built actions created by the community for common tasks like checking out code, setting up a specific programming language, or deploying to a cloud provider. This component-based approach makes it easy to build complex and powerful workflows with minimal custom scripting.