What is up time?

[qbeststar]

anyone knows what is up time??? please explain me in detail.

Uptime is a measure of system reliability, expressed as the percentage of time a machine, typically a computer, has been working and available.

[techinfo]

Uptime is a measure of system reliability, expressed as the percentage of time a machine, typically a computer, has been working and available.

[klasstaffan]

Uptime describes how long or how reliably a system has been running. It may be defined as an absolute value (e.g., 64 days) or a percentage (e.g., 99.5%). Uptime percentage is a common metric used to determine the reliability of a web server.