The combinatorial clock auction (CCA) is a new type of auction that helps bidders find the best deals on multiple items. It works like a game where bidders can figure out what they want as they go along. This auction is based on the Vickrey auction, which is known for being fair and efficient. The CCA makes it easier for bidders to participate by letting them bid on different combinations of items. This makes it more practical for real-world use.