In computer terms a bit refers to a single 1 or 0 in a binary number. 8 bits taken as a single unit form a byte. 4 bits as a single unit form a nibble. Generally 16 bits (2 bytes) is referred to as a WORD, 32 bits (4 bytes) a DWORD (for double word), 64 bits 8 bytes a QWORD (for quad word).