A data backup is a copy of computer data that is stored in a separate location from the original data so it can be used in case of data loss. The process of backing up data can be automated or done manually. Backups can be stored locally on internal or external hard drives or remotely online via network servers or cloud storage systems. A common best practice for backups is the “3-2-1 rule,” where there are at least 3 copies of the data stored on 2 different types of storage media with 1 backup copy kept offsite (in a remote location). This type of data backup distribution helps minimize the possibility of total catastrophic data loss. Data backups can be stored in various ways, such as in compressed file formats (like .zip files), in regular file formats and folder structures, in a shared cloud drive where they are instantly accessible, or in a dark archive where accessibility is limited.
This video covers the basics of data backups, including why and how they are done: https://www.youtube.com/watch?v=FIL6L7f32Bs
This guide presents a comprehensive overview of backups, including a brief history of backups and definitions of different types of backups: https://www.techtarget.com/searchdatabackup/definition/backup