What is CI/CD and where does QA fit?

Continuous Integration (CI): every code commit triggers an automated pipeline that builds the code, runs unit/integration/lint checks, and reports the result within minutes. The goal is fast feedback — break-and-fix in five minutes, not at the end of a sprint.

Continuous Delivery (CD-delivery): after CI passes, the build is automatically packaged and deployed to a staging environment, ready for manual promotion to production.

Continuous Deployment (CD-deployment): takes that one step further — automated deploy all the way to production whenever CI/CD checks pass. No manual gate.

Where QA fits — three concrete responsibilities:

1. Author the automated tests that run in CI: unit, integration, contract, E2E, performance smoke. The test suite is the quality gate.
2. Define what blocks the pipeline. Failing tests block, falling coverage blocks, critical security findings block. Subjective things (code style preferences) often don't.
3. Maintain pipeline health. Flaky tests get triaged or quarantined. Test runtime stays under target. Failures get root-caused, not retried.

In a healthy team, QA isn't a separate phase before release — it's continuous, automated, and the pipeline enforces it. The QA engineer's job evolves from "test before release" to "design the system that tests on every commit."