32-bit is a term applied to processors, and computer architectures which manipulate the address and data in 32-bit chunks. It is also a term given to a generation of computers where 32-bit processors were the norm.
In computer architecture, {{{1}}}-bit integers, memory addresses, or other data units are those that are {{{1}}} bits {{{2}}} wide. Also, {{{1}}}-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers, address buses, or data buses of that size.
The range of integer values that can be stored in 32 bits is 0 through 4294967295, or -2147483648 through 2147483647 using two's complement coding. Hence, a 32-bit processor can address 4GB of byte-addressable memory.
The external address and data buses are often wider than 32 bits but both of these are stored and manipulated internally in the processor as 32-bit quantities. For example, the Pentium Pro processor is a 32-bit machine, but the external address bus is 36 bits wide, and the external data bus is 64 bits wide.
See also: 32-bit application, 32-bit era, 16-bit, 16-bit application, 64-bit