A network switch is the device that connects wired equipment in a store or venue to the local network. Tills, printers, access points, cameras and servers plug into it, and it passes data between them and out to the router.
Unlike a simple hub, a switch learns which device is on which port and sends traffic only where it is needed. Unmanaged switches work out of the box with no settings. Managed switches add features such as VLANs for separating guest and POS traffic, monitoring, port control and PoE power management.
Small shops may need only one 8 or 16-port switch, while larger stores and kitchens use several, linked together, often in a locked comms cabinet. Venues that segment their network or run many cameras and access points usually need managed, PoE-capable models. Labelling ports and keeping a simple diagram of what plugs into where makes faults far quicker for a support technician to trace.
Pitfalls include buying consumer-grade switches for a busy commercial environment, running out of ports, overheating in a closed cupboard, and forgetting that a switch is a single point of failure. Keep spare capacity and consider a spare unit and a UPS for critical sites.
It is a quiet piece of equipment, but when it fails, every device connected to it goes offline.