Downtime
The time when the computer, computer network, or online program or service is not functioning due to hardware or software issues. Network routers, other network equipment, and online services may state what the average downtime or uptime is to help give the customer a better understanding of what they can expect from the product or service as far as reliability. For example, a 1% or .1% downtime guarantee lets the customer know that at most the device will only experience a very minimal downtime during it's lifetime use.