Variation

Also called: flag variation, feature flag variation

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A variation is a value a feature flag can serve. A boolean flag has two variations, on and off, and a multivariate flag defines several (strings, numbers, or JSON payloads) and each evaluation returns exactly one. The flag's rules, rollout, and default all resolve to a variation, and that value is what your code branches on.

Boolean and multivariate variations

The common case is a boolean flag with two variations, read through a helper like boolVariation. A multivariate flag has three or more (string, number, or JSON), which is what powers an A/B test with several arms, tiered limits per plan, or a config payload delivered as a flag. Each variation has a stable key, and evaluation serves one of them to each user.

How a variation is chosen

Evaluation works through the flag in order: prerequisites, then targeting rules, then any percentage rollout, then the fallthrough default, and every path ends at exactly one variation, returned with a reason explaining the choice. Sticky bucketing keeps a given user on the same variation across evaluations, so what they see stays stable as you ramp a rollout or run an experiment.

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Related terms

Feature flag

A feature flag is a conditional in your code whose value is controlled from a remote dashboard, letting you turn functionality on or off without deploying new code.

Multivariate testing

Multivariate testing compares more than two variations at once (often combinations of several changes) to find which performs best, extending an A/B test beyond a single either/or split.

Flag evaluation

Flag evaluation is the process an SDK runs to decide which variation a feature flag returns for a given user, applying prerequisites, targeting rules, and rollouts to the user context.

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