The four basic parts of an assembly language instruction are:

Mnemonic $($required$)$: A short abbreviation that represents the operation to be performed, such as ADD, SUB, MOV, etc.

Operand$($s$)($required$)$: One or more values that specify the data or memory locations to be operated on$.$ Operands can be registers, memory locations, or immediate values.

Prefixes $($optional$)$: Special prefixes can be added to the instruction to modify its behavior, such as the LOCK prefix, which ensures that the instruction is executed atomically.

Suffixes $($optional$)$: Some instructions support suffixes to specify the size of the operands, such as the BYTE, WORD, or DWORD suffixes.