10BASE2 (also known as cheapernet, thin Ethernet, thinnet, and thinwire) is a variant of Ethernet that uses thin coaxial cable terminated with BNC connectors to build a local area network.

During the mid to late 1980s this was the dominant 10 Mbit/s Ethernet standard.

The use of twisted pair networks competed with 10BASE2's use of a single coaxial cable. In 1988, Ethernet over twisted pair was introduced, running at the same speed of 10mbps. In 1995, the Fast Ethernet standard upgraded the speed to 100mbps, and no such speed improvement was ever made for thinnet. By 2001, prices for Fast Ethernet cards had fallen to under $50. By 2003, Wi-fi networking equipment was widely available and affordable.

Due to the immense demand for high-speed networking, the low cost of Category 5 cable, and the popularity of 802.11 wireless networks, both 10BASE2 and 10BASE5 have become increasingly obsolete, though devices still exist in some locations. As of 2011, IEEE 802.3 has deprecated this standard for new installations.