must identify and eliminate potential causes of downtime
caused by hardware failures
network glitches
software problems
application bugs, and so forth
Sometimes, poor server, application, or network performance is perceived as downtime.
EX: surfing the Web, users expect the first visual frame of a Web page within a few seconds of accessing the site.
Therefore, All systems, especially those related to consumers and critical operations, should always be ready and must operate with no lost transactions