This document provides an overview of Ethernet and discusses its frame structure, operation as an unreliable and connectionless protocol, and use of Carrier Sense Multiple Access with Collision Detection (CSMA/CD) as its medium access method. It describes the Ethernet frame format and how switches encapsulate IP datagrams into Ethernet frames for transmission. It explains that Ethernet is unreliable and connectionless, and how gaps in received datagrams are handled. It then details the CSMA/CD algorithm, including how adapters sense the channel before transmitting, abort transmissions upon detecting collisions, and employ exponential backoff to space out retransmission attempts. State diagrams and flow charts are provided to illustrate the CSMA/CD process.