Uptime is the duration of time that a system has been working and available in a reliable operating manner. It is an indication of the stability and reliability of the operating system, and compute infrastructure. Downtime is the duration of time that a system is not available because it has suffered an unplanned outage or has been shut down as planned maintenance. System uptime and downtime are the inverse of each other. A system that has a high uptime will have a low downtime and the other way as well.