An Arithmetic Logic Unit (ALU) is a crucial component of a computer's central processing unit (CPU). It performs basic arithmetic operations like addition and subtraction, as well as logical operations such as AND, OR, and NOT. The ALU takes input data, processes it according to specified instructions, and produces output results. The ALU works in conjunction with other parts of the CPU, including the control unit and registers. It is essential for executing instructions in computer programs, enabling tasks ranging from simple calculations to complex data processing. Overall, the ALU plays a vital role in the functionality of modern computers.