A thread may be just created, running, blocked, terminated but not joined, etc.

Each of these different situations is referred to as the thread state. The thread control block records the state and uses it to know what transitions between states are allowed or appropriate.

Abstractly we might describe the possible thread states as in chapter 4:

• Runnable
• Running
• Waiting
• Terminated

Thread control is responsible for implementing the transitions between the states and updating the states as threads proceed from creation to destruction.