This document discusses data validation. It defines data validation as ensuring programs use clean, correct and useful data by using validation rules to check data entered is right, meaningful and secure. It describes methods for checking validity like manual reviews, auto checks and having providers review data. The document also distinguishes between validation, done by software to check data types and formats, and verification, done by users to check values are entered correctly without mistakes. It provides examples of validation types like format, presence, range and lookup checks.