Why to back up your computer
It is a good idea to create a backup of your system and files as often as you can so that you do not lose them. Your files can get lost for many unexpected reasons, like theft, if you spill water on your computer, or if your computer otherwise stops working.
Backing up your files simply means making a copy of them for safekeeping. This is done in case the original files become unusable due to loss or corruption. These copies can be used to restore the original data in the event of loss. Copies should be stored on a different device from the original files. For example, you may use a USB drive, an external hard drive, a CD/DVD, or an off-site service.
The best way to back up your files is to do so regularly, keeping the copies somewhere other than where you keep your computer to avoid theft or them being lost all together, and encrypting them.