There are a couple but the most common is the star
Star Topology
The client-server topology.
he most commonly used network topology is a hybrid topology called the Star Bus TopologyRead more: http://wiki.answers.com/What_is_network_topology_and_give_an_example_of_the_most_common_network_topology#ixzz1TrCMGlb6
Bus topology
Yes, peer to peer can be implemented in linear bus topology.
hierarchical (extended) star topology
Different types of Networking topologies are 1] Bus topolgy 2] Ring topology 3] Mesh topology 4] Hibrid topology
Bus star ring mesh hybrid
Ethernet is easily the most common topology having replaced token ring in the 90's. Simply because of it's ease of use with CAT5 cabling, cheap networking hardware and not needing any termination.
Topology refers to the physical method of wiring the devices to each other, what kind of connection devices are used, etc.
STAR
Star network,ring network,tree network,bus network