What is the difference between a router, switch, and hub?

Hub broadcasts data to all ports (Layer 1) - all devices receive all traffic, collisions occur, inefficient. Switch forwards data only to the destination port using MAC address table (Layer 2) - reduces collisions, more efficient. Router forwards data between different networks using IP addresses (Layer 3) - makes routing decisions, connects LANs, provides NAT, firewalling. Hubs are obsolete; switches for LAN, routers for WAN/Internet.