A network hub is a basic networking device that connects multiple computers or devices within a local area network (LAN). It operates at the physical layer of the OSI model, meaning it does not filter or manage data traffic. Instead, it simply receives incoming data packets and broadcasts them to all connected devices, regardless of the intended recipient. While network hubs are simple and inexpensive, they are less efficient than more advanced devices like switches. Hubs can lead to network congestion since all devices share the same bandwidth, making them less suitable for larger or more complex networks.