USB debugging is a developer mode in Android phones that allows newly programmed apps to be copied via USB to the device for testing. It is a way for an Android device to communicate with the Android SDK (Software Developer Kit) over a USB connection. It allows an Android device to receive commands, files, and the like from the PC, and allows the PC to pull crucial information like log files from the Android device. USB debugging is often used by developers or IT support people to connect and transfer data from an Android device to a computer. It is also used to synchronize with the computer data and its contents.

To enable USB debugging, you need to go to the Developer options in the device system settings. The location of the option varies depending on the Android version. For example, in Android 9 and higher, you can find it in Settings > System > Advanced > Developer Options > USB debugging. However, leaving USB debugging enabled keeps the device exposed when its plugged in over USB, which can be a security risk. Therefore, some organizations require users to turn off USB debugging.