One of the challenges of Continuous Delivery (CD) arises when a feature spans multiple commits, and an urgent fix needs to be released before the development of that feature is complete. When a feature is completed and deployed to production, teams also need a way to experiment safely, beta testing with a small group of users and being able to roll back quickly if an undesirable experience is observed. Feature toggles to the rescue. This article explains this practice, which was common twenty years ago and is being rediscovered today.