A half subtractor is a digital logic circuit that performs binary subtraction of two single-bit binary numbers. It has two inputs, A and B, and two outputs, DIFFERENCE and BORROW. The DIFFERENCE output is the difference between the two input bits, while the BORROW output indicates whether borrowing was necessary during the subtraction. The half subtractor can be implemented using basic gates such as XOR and NOT gates. The circuit diagram, truth table, and characteristic equation of a half subtractor are available in the search results. The half subtractor is a basic building block in digital circuits and is commonly used in applications such as arithmetic circuits, data processing, and computer memory.