While the two terms are often used interchangeably, assembly language is a more “user friendly” translation of machine language. Machine language is the collection of patterns of bits recognized by a central processing unit (CPU) as instructions. Each particular CPU design has its own machine language. The machine language of the CPU of a microcomputer generally includes about 75 instructions; the machine language of the CPU of a large mainframe computer may include hundreds of instructions. Each of these instructions is a pattern of 1s and 0s that tells the CPU to perform a specific operation.

Assembly language is a collection of symbolic, mnemonic names for each instruction in the machine language of its CPU. Like the machine language, the assembly language is tied to a particular CPU design. Programming in assembly language requires intimate familiarity with the CPU’s architecture, and assembly language programs are difficult to maintain and require extensive documentation.

The computer language C first developed in the late 1980s, is a high-level programming language that can be compiled into machine languages for almost all computers, from microcomputers to mainframes, because of its functional structure. It was the first series of programs that allowed a computer to use higher-level language programs and is the most widely used programming language for personal computer software development. C was first released in 1985 and is still widely used today.