Rsync Differential Backup vs Incremental Backup

What is the difference between differential backup and incremental backup
Differential backup is the backup of changed files since the last full backup
Incremental backup is a backup of changed files since the last incremental backup
Introduction of backup types and combined backup solutions

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Full backup

Backing up all selected folders does not rely on the archive attributes of the files to determine which files to back up.
(During the backup process, any existing marks are cleared and each file is marked as having been backed up, in other words, the archive attribute is cleared).

Differential backup

Differential backup is for full backup: back up all the files that have changed since the last full backup.
(During the differential backup process, only those selected files and folders that are marked are backed up. It does not clear the mark, that is: the file is not marked as backed up after the backup, in other words, the archive attribute is not cleared).
Incremental backup
Incremental backup is for the last backup (no matter what kind of backup): back up all files that have changed since the last backup.
(During the incremental backup process, only the selected files and folders that are marked are backed up. It clears the mark, which means: mark the file after the backup, in other words, clear the archive attribute.)

Examples of combinations of different backup types

Full backup and differential backup
A full backup is performed on Monday, and a differential backup is performed from Tuesday to Friday. If the data is destroyed on Friday, you only need to restore the full backup on Monday and the differential backup on Thursday. This strategy requires more time to back up data, but less time to restore data.
Full backup and incremental backup

A full backup is performed on Monday, and an incremental backup is performed from Tuesday to Friday. If the data is damaged on Friday, you need to restore the normal backup on Monday and all incremental backups from Tuesday to Friday. This strategy requires more time to back up data, but less time to restore data.

1. Normal backup is used to copy all selected files and mark each file after backup (in other words, clear the archive attribute). In other words, a normal backup is to copy all the files to be backed up, and clear the "archive" attribute of all documents after the backup, so that the software will think that these files have not been backed up the next time they are backed up.
2. Incremental backup is another form. It only backs up files created or changed since the last normal or incremental backup, and marks these files as having been backed up. For example, when you perform a normal backup for the first time, the "archive" attribute of all documents is cleared, and after you create or modify these files, the files are re-added with the "archive" attribute. Incremental backup is to back up these Files, and clear the "archive" attribute of these files after backup to ensure that these files will not be backed up next time.
3. Differential backup is used to copy files created or changed since the last normal or incremental backup. It does not mark the file as having been backed up (in other words, the archive attribute is not cleared). This means that normal or incremental backup removes the "archive" attribute of the file. After a new file is created or the old file is modified, the file is re-added with the "archive" attribute. Differential backup is to back up this type of file. After the backup is completed, the differential backup will not clear the "archive" attribute of such files. In this way, when the differential backup is run next time, as long as the files in the last differential backup have not been changed during this period, they will also contain In the backup set, it will be backed up again.

Give a more general backup strategy as an example to help you understand. Make differential backups on Sundays, incremental backups at other times, and full backups on Sundays every four weeks.

Incremental backup is to compare files (or increase, decrease, or change) that are different from the last backup.
Differential backup is actually an incremental backup, but it is not a comparison of the last time, but the difference between the current day and the last full backup.

So what are the benefits of this backup strategy? For example, if your system has a problem, you need to back up to the state before January and 13 days, then you only need to use a full backup, add a recent differential backup, and add a few consecutive days of incremental backup, you can Restore the state you want.