Data validation is a checking procedure that a computer carries out automatically to help reduce input errors in data. A common type of data validation is the spell-checker function, which is used to check for spelling and grammar errors when typing in a word processing document.

Some confusion exists in the definition of data validation because the validation process does not check that the data is correct. For example, if one inputs letters into a field that states it is for numbers and in the format of _ _ / _ _ / _ _ , the computer flags this as a data-validation error. However, if one inputs 01/09/14 into the field when the date should be entered as 09/01/14, the computer sees this as still valid.