reliability means the probability of device that device will perform for given time interval under given condition
or

probability of device that will fail during certain level of time

what is use of reliability function ?

failure occur when device stop working
failure rate probability of device that the device will fail per unite of time

what is mean time to failure and mean time between failure ?

 

These are used to estimate how long a device will operate before requiring repair. The more often a device needs to be repaired, the higher the overall cost of a product.

Failure rate could also refer to the normalized failure rate of components within a device, as compared to the overall failure rate of the device on the whole. This failure rate would be useful in determining the most probably cause of failure in hopes of reducing repair time.

Another number related to these is the mean time between failure (MTBF), which is the average amount of time the device will operate properly.

 

can you tell me what is difference between stochastic process and Markov process. both are same are different

 

The latter is a subset of the former. See here.