Machine code, also known as machine language, is a low-level programming language that consists of binary instructions understood directly by a computer’s hardware. It is the lowest level of abstraction that humans typically interact with when programming a computer.

Machine code is specific to the architecture and hardware of a particular computer system. Each processor or microcontroller has its own set of instructions, and machine code provides a way to communicate with and control the hardware at a fundamental level.

In machine code, instructions are represented as binary numbers composed of 1s and 0s, which directly correspond to specific operations performed by the computer’s central processing unit (CPU). These operations can include arithmetic calculations, data movement, logical operations, branching instructions, and input/output operations.

Here’s an example of machine code instructions for a hypothetical processor:

10110000 00100011 01001001 00000001

These binary numbers would be interpreted by the processor as specific commands to perform a particular operation. However, machine code is not human-readable, and it can be challenging and time-consuming to write and understand directly. Therefore, higher-level programming languages and assemblers are commonly used to write programs, which are then translated into machine code by a compiler or assembler before execution.