What Is a Feature Flag?

A feature flag is a runtime switch that controls whether a piece of functionality is active, allowing code to ship disabled and be enabled later without a new deploy. Flags can target subsets of users for gradual rollout. They separate the act of deploying code from the act of releasing a feature.

Why it matters

Coupling release to deploy makes risky launches all-or-nothing. Feature flags let code merge and deploy continuously while exposure is controlled and reversible with a toggle. The cost is flag lifecycle hygiene, since stale flags accumulate complexity if never removed.

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