Dash cameras record on a loop, continuously deleting old footage to make for the new stuff. The idea is that you only need to save the footage when an incident happens, right? A good dash camera will have a sensor that can detect crashes and automatically lock the video in storage, so you don’t have to think about it in the wake of an accident. Some cameras have built-in GPS, so it can overlay location data as well as your speed of travel. Some have Wi-Fi, too, enabling you to quickly transfer an important video to your phone so you can share it.