How does a CI/CD pipeline work? How do you create one, and what does it look like?

A CI/CD pipeline automates the process of building, testing, and deploying code. Continuous Integration (CI) focuses on merging code changes into a shared repository frequently, triggering automated builds and unit tests. Continuous Delivery (CD) extends CI by automatically pushing successful builds to staging or production environments, often with manual approval gates. A typical pipeline consists of stages such as Source (fetch code), Build (compile and package), Test (unit, integration, security), Deploy (to test or prod), and Monitor (collect metrics). Tools like GitHub Actions, GitLab CI, Jenkins, or CircleCI define pipelines as code (YAML, JSON). For example, a GitHub Actions workflow might trigger on push, run tests, build a Docker image, push it to ECR, and deploy to an ECS cluster. The pipeline is visualized in the CI tool’s UI, showing each job’s status, logs, and artifacts. Key best practices include keeping pipelines idempotent, using environment variables for secrets, and implementing rollback strategies.