DEADLOCKS

deadlock as the name itself says that what it is...
                                  It can be tabulated in such a way that it is the problem occers in the operating system while executing a bulk of processess in the queue that could be understand in the way that on this stage when  our cpu performance reaches to the highetst level that is at 100% usage. so at this time or situation we could not do our work and our processes are being deadlocked and so our system get hanged..
 The name hang means that we or the user could not get the output or the executions at the time he wants..
At this situation only the TASK MANAGER works in our system as if it has a highest priority amongst all the processes here we could see the numerous processes running and waiting....
 the figure shown says the defination of the deadlock itself ie. see below:

the next image could help u in defining and xplaining the dead lock

the deadlock constitute some essential conditions they are:
1. Mutual Exclusion
2. resource holding
3. circular wait
4. no preemption