Ethernet refers to a collection of standards coming from the IEEE (Institute of Electrical and Electronics Engineers).
These standards are used to connect one or several computers to a network, forming a LAN.
All start by the number 802.3:
Note: BASE refers to baseband signaling, and the letter(s) after it refers to the cable that is used to carry the signal. For example:
T = twisted-pair
SR = short-range
Resources:
Jeremy’s IT Lab: Free CCNA | Interfaces and Cables | Day 2 | CCNA 200-301 Complete Course
AD-net: OSI Layer 1 – Ethernet