Facebook's newest tool, known as Safety Check, aims to allow people to quickly alert friends and family that they are safe after a natural disaster. For instance, if an earthquake is detected in the area Facebook predicts a user is located, Safety Check sends a notification asking whether the user is OK. After responding, a user can check off friends he or she knows to be safe. Facebook says, "we hope it's a tool that helps you stay connected to those you care about, and gives you the comfort of knowing your loved ones are safe." Check out how it works before you need to use it in an emergency situation.