Thread

Threads
A process is a program that performs a single thread of execution. This single thread of control allows the process to perform only one task at one time. Many modern operating systems have extended process concept to allow a process to have multiple threads of execution thus allowing the process to perform more than one task at a time.

A thread, sometimes called a lightweight process (LWP), is a basic unit of CPU utilization; it comprises a thread ID, a program counter, a register set, and a stack. It shares with other threads belonging to the same process its code section, data section, and other operating-system resources, such as open files and signals. A traditional (or heavyweight) process has a single thread of control. If the process has multiple threads of control, it can do more than one task at a time.

Many software packages that run on modern desktop PCs are multithreaded. An application typically is implemented as a separate process with several threads of control.