Availability

Ensuring that information systems and the necessary data are available for use when they are needed. Traditionally, computer systems were made available for staff use by the IT department in the early morning, and then closed down again by the IT staff before running their 'End of Day' routines. Availability was thus the poor relation of Confidentiality and Integrity in security terms. However the extension of the working day (for example because of trading with different time zones) and the growth of 24x7 systems, associated with e.g. web sites, Internet (on-line) trading, cash point machines, coupled with the threats of viruses and intrusions means that availability has become a much more important element of Information Security work.