Uplink Port is a port on a hub that is used to connect the hub to another hub on an Ethernet network. Uplink ports allow hubs to be cascaded to form larger networks by using ordinary unshielded twisted-pair (UTP) patch cables and not using up any of the station ports on the hub that are used to connect computers. If you do not have an uplink port on your hub, you can still connect a station port on the hub to a station port on another hub by using a crossover cable. Hubs are typically connected in a cascaded star topology.
Be sure that the root or main hub of your cascaded star arrangement of hubs is a high-quality hub. Do not create collision domains larger than about 150 computers - network performance can seriously degrade due to too many collisions on the network. If hubs cannot meet your bandwidth requirements, consider replacing the main hub with an Ethernet switch.