What is the difference between Continuous Integration, Continuous Delivery, and Continuous Deployment?

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Three distinct (but related) practices on a spectrum of automation. Continuous Integration (CI) — developers frequently merge code into a shared branch (typically multiple times per day). Each merge triggers an automated build + tests. Goal: catch integration bugs early. Continuous Delivery (CD) — every change that passes CI is automatically prepared for production deployment (built, tested, packaged), but the actual deploy to prod requires a manual approval / button push . Goal: code is always in a deployable state. Continuous Deployment — every change that passes CI/CD is automatically deployed to production with no manual gate. Goal: zero-touch delivery; only failed tests block release. Spectrum: CI → Continuous Delivery → Continuous Deployment, each adding more automation. Don't conflate Continuous Delivery and Continuous Deployment — that's a classic interview trap. Delivery = always shippable, manual approval. Deployment = fully automated to prod, no manual step.