Feature Flag
intermediateDefinition
An on/off switch in an app's settings that turns a feature on or off for some or all users without releasing new code.
In the wild
A gym's new class-booking page ships turned off, and the gym switches its feature flag on for staff first, then for every member a week later.
More from DevOps & Deployment
Blue-Green Deployment
Releasing a new version by setting it up on a second, identical copy of the live system and then switching all visitors over at once, so you can switch back just as fast if something breaks.
Canary Release
Giving a new version to a small share of users first and watching for problems before letting everyone else have it.
CI/CD (Continuous Integration / Continuous Delivery or Deployment)
Automation that tests every change as soon as it's shared (continuous integration) and then gets passing changes ready to release or releases them automatically (continuous delivery or deployment).
Container
A sealed package holding an app plus everything it needs to run, so it behaves the same on any computer.
Deployment
Putting a new version of an app or website live so real people can use it.
Docker
The most widely used tool for building and running containers, the sealed packages that hold an app and everything it needs.