What is live lock and deadlock? what is Lock escalation?

In SQL Server Live Lock occurs when read transactions are
applied on table which prevents write transaction to wait
indefinitely and Deadlocking occurs when two user processes
have locks on separate objects and each process is trying to
acquire a lock on the object that the other process has.

Lock escalation is the process of converting a lot of low
level locks (like row locks, page locks) into higher level
locks (like table locks).