Question : Persistent and non-persistent connection

What is the difference between persistent and non-persistent connection?
And When do we use persistent connection not non-persisten connection and vice versa?

Answer : Persistent and non-persistent connection

It depends on what you are refering to.

If you are using routing on a PC and want to add a route to your routing table a /p at the end would make it persistent.
When mapping a network drive a /persisent makes the drive persisent.

A no-persistent connection or route exists until you reboot your PC. Next startup the route or network drive is gone.
Persistent makes it permanent until you manually remove it even if you keep restarting you PC.