The Ring doorbell is one of the most popular home-security devices on the market. BrandonKleinVideo/Shutterstock The Ring doorbell works by allowing you to see who's at your door whenever there's motion detected, even if you're not home. You can see what's happening through the Ring app on your phone and speak through the doorbell. The app also has several other useful features to make your home more secure. Visit Business Insider's Tech Reference library for more stories. You've probably heard something about the increasingly popular Ring doorbell.