Ethernet (10BASE2)
10BASE2 (also known as cheapernet, thin Ethernet, thinnet, and thinwire) is a variant of Ethernet that uses thin coaxial cable (RG-58A/U or similar, as opposed to the thicker RG-8 cable used in 10BASE5 networks), terminated with BNC connectors. During the mid to late 1980s this was the dominant 10 Mbit/s Ethernet standard, but due to the immense demand for high speed networking, the low cost of Category 5 Ethernet cable, and the popularity of 802.11 wireless networks, both 10BASE2 and 10BASE5 have become increasingly obsolete, but still exist in many locations.

Picture info, from top left to right bottom,
BNC cable connector this end connects to a nic card or T piece.
Network Interface Card BNC connector.
BNC-T piece for connecting more computers on the same wire.
BNC terminator for terminating the signal in one end so the signal doesn't bounce around creating problems.
The last piece is a "repeater" just connect one cable to each end.

10BASE2 coax cables had a maximum length of 185 meters.
The maximum practical number of nodes that can be connected to a 10BASE2 segment is limited to 30. In a 10BASE2 network, each segment of cable is connected to the transceiver (which is usually built into the network adaptor) using a BNC T-connector, with one segment connected to each female connector of the T.