An Ethernet switch is a networking device that connects multiple devices within a local area network (LAN). It uses packet switching to receive, process, and forward data to the destination device, ensuring efficient communication between computers, printers, and servers. By creating a dedicated connection for each device, it reduces network congestion and improves overall performance. Ethernet switches operate at the data link layer of the OSI model, using MAC addresses to identify devices on the network. They come in various sizes, from small, unmanaged switches for home use to larger, managed switches for enterprise environments, allowing for advanced features like traffic management and security.