Backups are important to ensure that you always have access to all of your data, even if your computer crashes, or gets stolen.
The easiest way is to use an external storage service, (e.g. iCloud for iPhones or OneDrive), to automatically make backups.Please note that these are not generally considered to be privacy friendly solutions.
For increased privacy you can also opt to purchase an external hard drive, and create backups here. Here's an overview of Backup drives sold at Amazon.