Feature Flags

As Martin Fowler describes in his detailed guide, Feature Toggles (often also refered to as Feature Flags) are a powerful technique, allowing teams to modify system behavior without changing code. 

A feature toggle in software development provides an alternative to maintaining multiple feature branches in source code. A condition within the code enables or disables a feature during runtime. In agile settings the toggle is used in production, to switch on the feature on demand, for some or all the users. Thus, feature toggles do make it easier to release often.