A Full Adder is a digital circuit that not only produces a CARRY; it can even utilize that. Thus a Full adder can be better defined as a digital circuit that inputs three binary bits and adds them to produce a SUM and a CARRY. Among of the three input bits; first is the ADDEND, second is the AUGEND and third is the INPUT CARRY.
A Full Adder can be constructed by connecting two Half Adders serially. Consider the following Block Diagram: