Multithreading is a specialized form of multitasking. In general, there are two types of multitasking: process-based and thread-based. A process is, in essence, a program that is executing. Thus, process-based multitasking is the feature that allows your computer to run two or more programs concurrently.
A thread is a dispatchable unit of executable code. The name comes from the concept of a “thread of execution.”
In a thread-based multitasking environment, all processes have at least one thread, but they can have more. This means that a single program can perform two or more tasks concurrently. For instance, a text editor can be formatting text at the same time that it is printing, as long as these two actions are being performed by two separate threads.
The differences between process-based and thread-based multitasking can be summarized like this: Process-based multitasking handles the concurrent execution of programs. Thread-based multitasking deals with the concurrent execution of pieces of the same program.