What Does Uptime Mean?

Uptime is a metric that represents the percentage of time that hardware, an IT system or device is successfully operational. It refers to when a system is working, versus downtime, which refers to when a system is not working.

Techopedia Explains Uptime

One critical role of the terms uptime and downtime is defining the level of success provided by realtime services or systems. It can be difficult to quantify a service’s success or value without these terms. A service level agreement (SLA) or other real-time service contract may include uptime/downtime ratios that show how much time a service is expected to remain operational.