OpenMP is an application programming interface (API) that supports multi-platform shared memory multiprocessing programming in C, C++, and Fortran. It provides a set of compiler directives, library routines, and environment variables that enable developers to write parallel code easily. This allows programs to run faster by utilizing multiple processor cores simultaneously. By using OpenMP, programmers can add parallelism to their existing code with minimal changes. It is particularly useful for tasks that can be divided into smaller, independent subtasks, making it a popular choice in scientific computing, data analysis, and other performance-critical applications.