Mean time to failure

Mean time to failure is a measurement used to measure how long a machine or system will work before it stops working. It's like an average; it's not a guarantee that your system will keep working that long, but it is an educated guess based on how well it has worked in the past. So, if a system has a mean time to failure of 5 years, then it has been working well for 5 years on average and that's how long we expect it to last until it stops working.