Data Validation Data Validation is used to ensure data integrity. Data Integrity means the user typed in the value that belongs to the cell. Data Validation compares what the user types and alerts them if they typed something that did not match.   For example: Did your users enter today's date instead of number of hours in the time sheet? If they make a mistake Data Validation would alert them with an error message.   Better yet, the message would give them enough information to correct their mistake and try again.   1. Try it: Practice with Data Validation Select Cell B2. Delete any sample data, please. Go to Data ->Data Tools-> Data Validation.   Keep going... Exam 77-888: Microsoft Excel Expert 2010 2. Applying Formulas and Functions 2.4. Apply functions in formulas: Data Validation Data ->Data Tools-> Data Validation