Ensuring timely and reliable access to and use of information. SP 800-53; SP 800-53A; CNSSI- 4009; SP 800-27; SP 800-60; SP 800-37; FIPS 200; FIPS 199; 44 U.S.C., Sec. Response:

Availability, as a core principle of information security (CIA triad), specifically refers to ensuring authorized users can access information and systems when needed. This definition directly matches 'ensuring timely and reliable access to and use of information'.

Integrity refers to safeguarding the accuracy and completeness of information and processing methods, not access.

Confidentiality refers to protecting information from unauthorized disclosure, not timely access.

Capability refers to the ability of a system to perform its functions, which is a broader concept and not a core information security principle like availability.