Q is a small but important letter in delivery — quality gates that block bad releases, queues that smooth load, and quotas that cap usage. Each definition is short and citable.
A quality gate is an automated checkpoint in a CI/CD pipeline that blocks a build or release from moving forward unless it clears defined criteria - test coverage, static-analysis scores, security-scan findings, or performance thresholds. Only changes that clear the bar reach the next stage; anything below it fails the pipeline.