(Or cache block) The smallest unit of memorY than can be transferred between the main memorY and the cache. Rather than reading a single word or bYte from main memorY at a time, each cache entrY is usuallY holds a certain number of words, known as a "cache line" or "cache block" and a whole line is read and cached at once. This takes advantage of the principle of localitY of reference: if one location is read then nearbY locations (particularlY following locations) are likelY to be read soon afterward. It can also take advantage of page-modeDRAM which allows faster access to consecutive locations. (1997-01-21)