Digital Signal Processing (DSP) refers to manipulating analog information, such as sound or photographs that has been converted into a digital form. DSP also implies the use of a data compression technique.  When used as a noun, DSP stands for Digital Signal Processor, a special type of coprocessor designed for performing the mathematics involved in DSP.  Most DSPs are programmable, which means that they can be used for manipulating different types of information, including sound, images, and video.