All it is, is a wireless connection between two things. When you set your home network up you use a "router" to connect all of the different computers together. It used to be that you could only use wires, but now if your router has "wifi" then it is able to broadcast a signal to even more computers (or cell phones, or anything with "wifi capability") to connect them as well. Now all of the computers can communicate. If you have a wireless connection to your router, all of your computers that are connected to your router can access the internet.