Assembly language is a low-level programming language that provides a way for humans to write instructions that a computer's hardware can execute directly. Unlike high-level languages, assembly language is closely tied to the architecture of the specific computer or processor, making it extremely fast and efficient. However, it is more difficult to write and understand because it uses symbolic representations of machine code instructions. Assembly language is often used in situations where direct hardware control, speed, or resource efficiency is critical, such as in embedded systems or operating systems development.