A ripple carry adder is a type of digital circuit used for adding binary numbers. It consists of a series of full adders connected in a chain, where the carry output from one adder becomes the carry input for the next. This design allows for the addition of multi-bit numbers by processing each bit sequentially. The main advantage of a ripple carry adder is its simplicity and ease of implementation. However, its performance can be limited by the propagation delay, as each carry must ripple through all the adders before the final sum is available.