The main use of an Ethernet cable is to connect devices within a local area network (LAN). It facilitates wired communication between computers, routers, switches, and other network devices, enabling reliable data transfer at high speeds. Ethernet cables adhere to specific standards, with CAT5e, CAT6, and CAT6a being common categories that support varying data rates and distances. This technology is essential for establishing stable internet connections and facilitating networked applications in both residential and commercial settings, providing a robust alternative to wireless connections.