The chapter introduces the concept of OpenMP, a shared-memory parallel programming interface, and its evolution in response to the increasing complexity and demand for parallel computing. It highlights the limitations of instruction-level parallelism and the rise of shared-memory parallel computers (SMPs) in the 1980s, which allowed multiple processors to work on different tasks simultaneously. The chapter discusses the challenges of managing cache coherency in SMPs and the need for programmers to express parallelism explicitly. It outlines the history of OpenMP, its development by the OpenMP Architecture Review Board (ARB), and its widespread adoption across various platforms. The chapter also compares OpenMP with other parallel programming models like MPI and Pthreads, emphasizing the simplicity and flexibility of OpenMP for creating parallel programs. Finally, it provides an overview of the OpenMP framework, its support in different compilers, and its applications in various computing environments.The chapter introduces the concept of OpenMP, a shared-memory parallel programming interface, and its evolution in response to the increasing complexity and demand for parallel computing. It highlights the limitations of instruction-level parallelism and the rise of shared-memory parallel computers (SMPs) in the 1980s, which allowed multiple processors to work on different tasks simultaneously. The chapter discusses the challenges of managing cache coherency in SMPs and the need for programmers to express parallelism explicitly. It outlines the history of OpenMP, its development by the OpenMP Architecture Review Board (ARB), and its widespread adoption across various platforms. The chapter also compares OpenMP with other parallel programming models like MPI and Pthreads, emphasizing the simplicity and flexibility of OpenMP for creating parallel programs. Finally, it provides an overview of the OpenMP framework, its support in different compilers, and its applications in various computing environments.