Definition - What does Fast Ethernet mean?
Fast Ethernet is one of the versions of the Ethernet standard that enables the transmission of data over 100 megabits per second on local area networks (LAN). It was launched in 1995 and was the fastest network connection of its time.
Fast Ethernet is also known as 100 Base X or 100 Mbps Ethernet, and is defined by the IEEE 802.3u protocol.
Techopedia explains Fast Ethernet
Fast Ethernet refers to a number of standards that support and provide 100 Mbps data transmission speeds. It was initially designed for copper-based twisted pair cable networks and included the 100 Base-TX, 100 Base-T4 and 100 Base-T2 standards. The length of the cable in copper-based fast Ethernet was restricted to 100 meters and supported different cable categories. The fiber-based fast Ethernet standards 100 Base-FX, 100 Base SX, 100 Base BX and 100 Base LX10 use one or more strands and modes of fiber optics to transmit data. The range of fast Ethernet for fiber mode can be from 400 yards to up to 25 miles.
Fast Ethernet was completely backward compatible with 10 Base T networks.