Hubs have multiple ports from four to over 20 on a single device. For each port, the hub has an indicator light so if a segment of cable or NIC stops functioning you can figure out which computer has the problem. A star topology network with a hub will continue to function even when one of the connections goes down. For a home LAN, you'll probably use a stand-alone hub with 4 to 12 ports. Stand-alone hubs can be linked together to expand your network.
Larger networks use stackable or modular hubs which can accommodate many more computers.
Look for a standard, inexpensive hub rather than a managed one which comes with advanced features required by larger networks. Faster 100 Mbps hubs are the most expensive. You can usually save some cash by getting a home networking kit which typically includes a small 4-5 port hub plus NIC cards. Switches Switches are devices that perform the same function as hubs but operate more efficiently. When you send data through a hub it's forwarded to the entire LAN then read by the computer it's intended for.