Ethernet is a commonly used LAN technology. It was discovered at EXROX PARC(Palo Alto Research Center) in 1970s.Xerox, Intel and Digital described it in a standard so it is also known DIX standard. The standard is now started by IEEE in which 802.3 standard of IEEE describe formats, voltages of cable length etc.
The Ethernet needs bus topology. It needs a single coaxial cable. To which multiple devices connect. One Ethernet cable is sometimes known a segment. This segment is fixed to 500 meters in length. The minimum distance between connections is 3 meters.
The Ethernet speed was approximately 3Mbps, and the current standard is 10Mbps the fast Ethernet performs at 100Mbps. There are also gigabits Ethernet state now.
ENCODING USED IN ETHERNET:
The encoding needed in Ethernet is Manchester encoding. It uses signal modifies to encode data. e.g. A modification from positive voltage to 0 encodes as given in the figure below: