What are the Back up techniques available to store backup and which backup technique is most space efficient?

Answer 1

backup techniques are:- Full backup, differential backup, incremental backup.
Full Backup:A complete backup of every file

Differential Backup: Creates copies of all the files that are changed from the ones in the full backup

Incremental Backup:Copying changed files since the last full and differential backup

Incremental is the most space efficient, but a full backup should be taken 1st