GitLab CI/CD is a built-in continuous integration and continuous deployment platform that automates the entire software development lifecycle — from building and testing code to deploying it to production. Unlike tools that require third-party plugins or external services, GitLab CI/CD is natively integrated into GitLab, enabling teams to define workflows in a single .gitlab-ci.yml file at the repository root. What makes GitLab CI/CD powerful is its flexibility: you can run jobs in Docker containers, on Kubernetes, or on bare-metal servers; orchestrate complex pipelines with parent-child relationships and DAGs; and control exactly when jobs run with rules, variables, and environment-specific logic. The key mental model: pipelines are composed of stages, stages contain jobs, and jobs execute scripts — with every aspect configurable through YAML keywords that control execution order, dependencies, caching, artifacts, and deployment strategies.

---