A thread represents a concurrent execution unit within a process. Threads are characterized as light-weight processes (LWP). These are significantly easier to create and destroy. In many systems the creation of a thread is up to 100 times faster than the creation of a process. This is especially advantageous in situations when the need for concurrent operations changes dynamically.
Blocked: A thread might be in this state, when it is waiting for I/O operations to complete. When blocked, a thread cannot continue its execution any further until it is moved to the runnable state again. It will not consume any CPU time in this state. The thread scheduler is responsible for reactivating the thread.