POSIX Threads

POSIX Threads, usually referred to as "pthreads", is a programming model that allows a program to execute multiple actions seemingly at the same time by doing them in parallel. The API and libraries which give a program the ability to do this are available on most Unix-like systems and is available in most programming languages such as Java, C++ and Python.
Overview.
POSIX Threads allow programmers to implement programs that can do tasks in parallel. Because there is a standard for POSIX threads, they can be implemented across different hardware without many changes.