GitHub Actions Workflows: How to Create and Manage

GitHub Actions workflows are YAML-based CI/CD pipelines that automate software building, testing, and deployment processes. Workflows consist of jobs that run in parallel by default, with each job containing sequential steps. They're triggered by repository events like pushes, pull requests, or schedules. Key features include matrix builds for testing across multiple environments, job dependencies using the 'needs' keyword, environment variables, and concurrency controls. The platform supports reusable actions from the GitHub Marketplace and allows integration with external tools through custom actions.