Feature Toggle

Feature toggles (also called feature flags) decouple deployment from release. Code for a new feature is deployed to production but hidden behind a toggle. The feature is activated (toggled on) when ready, without a new deployment. Use cases include gradual rollout (enable for 10% of users), A/B testing (show different features to different user groups), and kill switches (quickly disable a problematic feature). Feature toggle management platforms like LaunchDarkly, Split.io, and Unleash provide dashboards, targeting rules, and analytics for managing toggles at scale.