This privacy requirement is one of the fair information practices. Individuals must be able to prevent the collection of their personal data, unless the disclosure is required by law. If an individual has choice about the use or disclosure of his or her information, consent is the individual's way of giving permission for the use or disclosure. Consent may be affirmative; i.e., opt-in; or implied; i.e., the individual didn’t opt out.

(1) Affirmative/Explicit Consent: A requirement that an individual "signifies" his or her agreement with a data controller by some active communication between the parties.

(2) Implicit Consent: Implied consent arises where consent may reasonably be inferred from the action or inaction of the individual.