This document discusses parallel processing. It begins by defining parallel processing as a form of processing where many instructions are carried out simultaneously by multiple processors. It then discusses why parallel processing is needed due to increasing computational demands and the limitations of increasing processor speeds alone. It classifies different types of parallel processor architectures including single instruction single data (SISD), single instruction multiple data (SIMD), multiple instruction single data (MISD), and multiple instruction multiple data (MIMD). The document concludes by outlining some advantages of parallel processing such as saving time and cost and solving larger problems, and provides examples of applications that benefit from parallel processing.