Is it valid or allowed, can check if something is valid but sometime inacurrate
You can check if it is not correct.
This ensure data is correctly inputted and spots human errors.
Ensures data entered complies with allowable data
many different types of validation include:
type character checks presence checks
Is it the same?
It is a number that is derived from the other contents of the number
Backing up and archivivng
full compies every file fully]
Only copies files that are changed in the last backup
not the same as backup
storing old/unused data
Taking it from server mainframe
Transferring onto storage medium
Unlikely to be used again but still available.