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 correct destination device. This helps improve network efficiency by reducing data collisions and ensuring that each device can communicate effectively. Ethernet switches operate at the data link layer of the OSI model, allowing them to manage data traffic based on MAC addresses. They can vary in size and capacity, accommodating small home networks or large enterprise systems, making them essential for modern networking solutions.