data validation

Data validation is the process of ensuring that a program operates on clean, correct and useful data. It uses validation rules to check for correctness, meaningfulness, and security of data that are input to the system. You use data validation to control the type of data or the values that users enter into a program. For example, you may want to restrict data entry to a certain range of dates, check that email addresses or phone numbers are in the correct format, that passwords are the correct length and of a certain level of strength, limit choices by using a list, or make sure that only positive numbers are entered, for example.