bus topology

Networks employing a bus topology use a common physical connection for communication. That means the physical media is shared between stations. When one station transmits on the bus, all devices hear the transmission. If more than one device transmits at the same time, the two transmissions will collide with each other and both transmissions will destroy each other.
When two or more of these devices attempts to access the network bus at the same time, some method must be used to prevent a collision (CSMA/CD). Historically, bus networks used coaxial cable as their medium of transmission. Token Bus, Ethernet (Thinnet and Thicknet) are common examples of bus topologies. Although some installations of Ethernet using coaxial cable still exist, all modern installations now use a hub and spoke or star topology.