1. The word audit has two meanings. The first is the security audit, whereby a consulting firm comes in and validates a companies security profile. This is similar to how accounting firms review a company's books. The second term is infosec specific, and means an "auditing" subsystem that monitors actions within the system. For example, it may keep a record of everyone who logs onto a system. Such a record is known as an audit trail. From Hacking-Lexicon