Assembly language is a low-level programming language that provides a direct representation of the machine code instructions used by a specific computer's Central Processing Unit (CPU). Unlike high-level languages, which use abstract structures and complex syntax, assembly language uses mnemonics—human-readable abbreviations (such as `ADD` or `JMP`)—that correspond nearly one-to-one with the processor's instruction set architecture. Programming in this language allows developers granular control over hardware resources, making it essential for writing operating system kernels, device drivers, and performance-critical sections of code where efficiency and direct memory access are paramount. Because assembly language is inherently tied to the instruction set of a particular processor, code written for one architecture cannot typically run on another without significant retooling.