A supercomputer is a high performance computing machine designed to work at extremely fast processing speeds. Supercomputers have many applications, including modelling simulations, performing complex scientific calculations, and rendering high definition 3D graphics. 

A Supercomputer is capable of processing PetaBytes of information per second.  That's an amazing 1,000,000,000,000,000 (ie a thousand trillion, or a quadrillion) instructions per second.