A special-purpose processing unit that assists the CPU in performing certain types of operations. For example, a math coprocessor performs mathematical computations, particularly floating-point operations. Math coprocessors are also called numeric and floating-point coprocessors.
Most computers come with a floating-point coprocessors built in. Note, however, that the program itself must be written to take advantage of the coprocessor. If the program contains no coprocessor instructions, the coprocessor will never be utilized.
In addition to math coprocessors, there are also graphics coprocessors for manipulating graphic images. These are often called accelerator boards.