Concept / Term · Established
Feature toggle / switch
A runtime switch that turns functionality on or off for selected users, separating code deployment from feature release.
Field note
A feature flag is a runtime decision point that can expose or hide functionality without redeploying the code. Rules may target staff, a test cohort, a percentage of users or a particular customer.
Also called a feature toggle or switch, the technique separated “deploying code” from “releasing a feature”—two events that older delivery processes often treated as the same thing.
Teams use flags for gradual rollouts, experiments, early-access programmes and emergency shut-offs when a new capability misbehaves.
It reduces launch risk, although forgotten flags create branching complexity and should be removed when their job is finished.
In a sentence“The new search is deployed, but its feature flag is enabled for only five per cent of users.”