Hub
A hub is just like a power strip. If you have a six-outlet power strip, it will let you plug in six the devices simultaneously. A hub has multiple RJ-45 ports for plugging in multiple CAT 5 cables from multiple computers. It receives and forwards data in packets and makes sure the data arrives at its destination in one piece.
Switch
A switch is similar to a hub in that multiple computers are connected to it using the same types of cables and ports. A hub transfers data to all the computers that are connected to it, whereas a switch transfers data only to specific computers. Which computers get what data depends on how you set up the switch. Switches speed up data transmission because they don't necessarily have to forward data to as many computers as hubs do. When you use a switch to transfer data to all the computers connected to it, the switch is acting exactly like a hub.
Router
A router connects multiple LANs or connects LANs with WANs. Routers have a more complicated job than hubs and switches because routers use the guidance information in data packets to determine the shortest route for getting those packets to their destinations. Some home users find routers useful for connecting more than two computers to a single DSL (Digital Subscriber Line) or other type of Internet connection, but simple home networks generally don't require a router.
