Threads exist within processes and share their resources. As illustrated in this Example, a process can contain several threads or, if no parallel processing is provided for in the program flow, only a single thread.

Threads are often referred to as lightweight processes that run independent of each other and each with its own set of instructions.

Threads vs Tasks

All threads in a process can access its shared memory. Threads also share other OS dependent resources such as processors, files, and network connections. As a result, the management overhead for threads is typically less than for processes. Threads, however, are not protected against each other and must carefully synchronize when accessing the shared process resources to avoid conflicts.

Threads in a process share the same address space which reduces overhead.

Similar to Processes, Threads exist in different states which is illustrated here: