An Ethernet cable is a type of network cable used to connect devices like computers, routers, and switches in a local area network (LAN). It allows for high-speed data transmission, enabling devices to communicate with each other and access the internet. These cables come in various categories, such as Cat5e, Cat6, and Cat6a, each supporting different speeds and bandwidths. The most common connectors used with Ethernet cables are RJ45 connectors, which ensure a secure connection between devices.