The word validation has several related meanings:

• In general, validation is the process of checking if something satisfies a certain criterion. Examples would be: checking if a statement is true, if an appliance works as intended, if a computer system is secure, or if computer data is compliant with an open standard. This should not be confused with verification.
• In computer security, validation also refers to the process of verifying that a user or computer program is allowed to do something.
• In psychology and human communication, validation is the communication of respect for a communication partner, which involves the acknowledgement that the other's opinion are legitimate.