There are various ways to back up your data. You can back up your data to an external device (see examples HERE) or you can back up your data to a cloud-based backup service, or back up your data to both an external device and a cloud backup service. You might even make more than one backup to external storage devices and keep the two copies in different places (providing protection and access to your data even if one of the backup devices is destroyed or inaccessible. Preserving your valuable documents and images for future access and use requires planning, as well as the use of automatic backup services.
Source: World Backup Day 2019