A Word, in computing, is the natural unit of data used by a particular processor design. The size of a word--measured in bits--is a fundamental characteristic of a computer's architecture. It typically represents the amount of data that the CPU can process at one time and the size of a memory address. For example, in a 16-bit processor, a word is 16 bits (2 bytes). In a 32-bit processor (like those used in the Windows XP era), a word is 32 bits (4 bytes).
In a modern 64-bit processor, a word is 64 bits (8 bytes). A larger word size generally means that the computer can process more data in each instruction cycle and can access a much larger amount of memory, leading to better performance, especially for data-intensive tasks. While the term "word" has this specific architectural meaning, it can sometimes be used more loosely in programming contexts to refer to a fixed-size group of bits, often 16 bits, for historical reasons. However, its primary definition relates to the native data size of the CPU.