### Definition >The property of being accessible and usable upon demand by an authorised entitity ^529e00 \- [[ISO 27000]] Information that is not available when it's needed is basically useless. These days, data and information is more needed than ever, which is a bit of a headache. At one end, there's zero availability but total confidence in its [[confidentiality]] and [[integrity]]: a state managed by locking it in a safe and throwing away the key. At the other end is publishing things on the internet: high [[availability]], but [[confidentiality]] is busted. This balance is going to come up again and again.