What are Threads?

A preemptive multi-tasking operating system supports multiple processes running in parallel by allocating each one a time slice.
Each process runs on its own address space. That is, it gets its own stack, heap, and other system resources.
Threads are units of execution that can run in parallel within one program. As such they:
- Start-up faster.
- Can easily communicate with each other. They can share variables.
- Can be better controlled by the programmer (not by the OS).
They allow a program to quickly and efficiently handle multiple asynchronous requests (e.g., requests coming from other machines).
Since they run in parallel, they exhibit many of the same problems that arise in distributed programming. They are also used in almost all distributed programming implementations.
You must learn to control your threads!