Kad is a P2P sharing network that uses a variant of the Kademlia protocol. It was created by the developers of eMule, and is incompatible with the Overnet network and intranet although both use essentially the same protocol.
Most Kad network users are also connected to eDonkey network servers. Kad clients typically query known nodes on the eDonkey network to find an initial node on the Kad network.
It’s like going to a party of collaboration, where each guest (customer) has a product and shares it with the rest of the guests at the party. Each of the guests have something to share, without a host (master server), each guest has served as the others who need it, and take from others what they want.