Blue-Green Deployment

In blue-green deployment, the current live environment is 'blue' and the new version is deployed to 'green'. Once the green environment is tested and verified, traffic is switched from blue to green. The blue environment becomes the rollback target. Advantages include zero-downtime deployments, instant rollback capability, and the ability to test in a production-identical environment before going live. Variations include canary releases (routing a small percentage of traffic to the new version first) and rolling deployments (gradually replacing instances).