(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)