64-bit refers to the number of bits (the smallest unit of information on a machine) that can be processed or transmitted in parallel, or the number of bits used for single element in a data format. When the term is used in conjunction with a microprocessor, it indicates the width of the registers #&151; a special high-speed storage area within the CPU. A 64-bit microprocessor can process data and memory addresses that are represented by 64 bits. The term is often applied to the following:
- microprocessor: indicates the width of the registers.
- graphics device, such as a scanner or digital camera
- operating system: refers primarily to the number of bits used to represent memory addresses.
See also 32-bit and “What Is 64-bit Computing?” in Webopedia’s Did You Know… section.