Hubs, switches, and routers are all important devices. They let us connect computers to other computers, network devices, or even to other networks. But what's the difference between a hub, a switch, and a router? Well it all comes down to how intelligent they are. 

Nicola and her friends have decided to stay in different hotels for their holiday. She wants to get a message to her friends Tasha and Mark who are both in a different hotel. Unfortunately, she doesn't know which hotel they're in. So she writes a quick note with her number and hotel room on it and tells them to get ahold of her. Then she photocopies the note and drops it off at every other hotel in the town. This is how a hub works. It isn't smart and any information that enters it will simply be broadcast to every output it's connected to. 

Now, imagine she does know which hotel they're in, but not exactly which room they're in. She can drop the note off at the hotel's reception and she can be pretty certain they'll get it to Tasha and Mark. This is how a switch works. It's smart enough to understand that certain data only needs to go to certain outputs, but that's about it. 

Okay, so now imagine she does know their room number. Now she can drop the note off and have it delivered to their room and be certain it will get to her friends. It is smart and can be programmed to deal with different kinds of data in specific ways.