A Gnutella-compliant client is a software application that follows the Gnutella protocol, a peer-to-peer file sharing protocol used to search for and exchange files over the Internet. It enables users to search for files on the Gnutella network, which is a decentralized network where users connect directly to each other to share files. This means that there is no central server controlling the network, and users are free to share any type of file they choose