A network switch is a device that connects multiple devices on a local network and forwards Ethernet traffic to the correct destination port. Unlike a simple hub, a switch learns which MAC addresses live on which ports, then sends frames only where they need to go. Many switches also provide VLANs, port security, link aggregation, and in some models Power over Ethernet for phones, cameras, and access points.
In cyber security, switches matter because they sit at the center of internal communication. If a switch is misconfigured or compromised, an attacker may be able to sniff traffic, redirect flows, or isolate devices. Defenders use switch logs, VLAN segmentation, MAC address controls, and firmware updates to reduce risk. Physical damage is also important: a damaged switch can interrupt connectivity or PoE power, creating outages that look like network attacks until the hardware is checked.