A
A/B Testing Flag
A feature flag used to split traffic between different versions of a feature for experimentation and optimization purposes.
C
Canary Release
A deployment strategy where new features are gradually rolled out to a small subset of users before full release, controlled by feature flags.
Circuit Breaker Pattern
A feature flag pattern that automatically disables features when they fail, preventing cascading failures in production systems.
D
Dark Launch
Deploying new code to production without making it visible to users, controlled by feature flags for testing in real production environments.
Dead Code
Code that is never executed because the controlling feature flag has been permanently disabled or the feature has been fully rolled out.
E
Environment-Specific Flag
Feature flags configured differently across development, staging, and production environments for environment-specific behavior.
Experiment Flag
A temporary feature flag used to conduct controlled experiments and measure the impact of new features on user behavior.
F
Feature Flag
A software development technique that allows teams to enable or disable functionality without deploying new code, also known as feature toggles.
Feature Flag Debt
The accumulated cost and complexity from maintaining obsolete or unnecessary feature flags in a codebase over time.
Feature Flag Lifecycle
The stages a feature flag goes through from creation to removal: development, testing, rollout, full deployment, and cleanup.
Flag Configuration
The settings that determine how a feature flag behaves, including targeting rules, percentage rollouts, and default values.
Flag Retirement
The process of removing feature flags and their associated code branches after they are no longer needed.
Flag Sprawl
The uncontrolled proliferation of feature flags in a codebase, leading to increased complexity and maintenance burden.
K
Kill Switch
An emergency feature flag that can instantly disable problematic features in production to prevent system failures or data corruption.
L
LaunchDarkly
A popular feature flag management platform that provides SDKs, APIs, and a dashboard for controlling feature releases across applications.
Long-Lived Flag
A feature flag intended to remain in the codebase indefinitely, such as kill switches or operational toggles.
M
MAU
Monthly Active Users — a billing metric used by feature flag providers like LaunchDarkly. The more users who trigger flag evaluations, the higher your bill.
Multivariate Flag
A feature flag that can have multiple values beyond simple on/off states, enabling complex feature variations and experiments.
O
Operational Toggle
A long-lived feature flag used for operational control, such as rate limiting, maintenance modes, or performance tuning.
P
Percentage Rollout
A feature flag configuration that enables features for a specific percentage of users, allowing gradual feature deployment.
Permission Toggle
A feature flag that controls access to features based on user permissions, roles, or subscription levels.
Progressive Rollout
The practice of gradually increasing the percentage of users who receive a new feature, monitored and controlled by feature flags.
R
Release Toggle
A temporary feature flag used to control the release of new features, typically removed after successful deployment.
Remote Configuration
The ability to change feature flag states without code deployment, typically through a management dashboard or API.
S
Split.io
A feature flag and experimentation platform that combines feature management with analytics for data-driven releases.
Stale Flag
A feature flag that is no longer serving its intended purpose, often at 100% rollout or 0% for extended periods.
T
Targeting Rules
Conditions that determine which users or segments receive specific feature flag variations based on attributes like location, device, or behavior.
Technical Debt
The implied cost of additional rework caused by choosing an easy solution now instead of using a better approach that would take longer.
Toggle Point
The specific location in code where a feature flag decision is made, determining which code path to execute.
Trunk-Based Development
A development practice where all developers work on a single branch, using feature flags to control feature visibility instead of long-lived branches.
U
Unleash
An open-source feature flag management system that provides a web UI and client SDKs for controlling feature toggles.
User Targeting
The practice of enabling features for specific users or user segments based on attributes like ID, email, or custom properties.
V
Variant
One of multiple possible values or configurations that a multivariate feature flag can return.