Server is a role that a program can play, meaning listening for incoming connections. Any computer can be a server.

Clients are programs that initiate the connection.

peer to peer

Aside from servers and clients, there is a third role in computer networks: peer.

In a peer to peer network, clients establish connections directly to other clients. Nodes in the network are symmetric with no fixed central servers.

Examples of peer to peer protocols:

• bittorrent
• webrtc

It's much trickier to set up. You don't "own" a server...

Webrtc