This document discusses combinational circuits and provides examples of half adders and full adders. It defines combinational circuits as those whose outputs only depend on the current inputs. A half adder is described as having two inputs (A and B) and two outputs (sum and carry), which can add two single bits. Its truth table and logic diagram using an XOR gate and AND gate are shown. A full adder handles three inputs (A, B, Cin) to add two bits along with a carry bit, with outputs of sum and carry out. Its block diagram and truth table are presented.