Do laptops run only on WiFi?
no if you dont have a router in your home of you do but it doesnt send out wifi (IE does not have 1 or 2 aerials coming from it ) then you will notice your laptop has an Ethernet slot that allows a wired connection from your Adsl modem or router
No, most of them also have a ethernet port on them too
No, almost all laptops also have a wired ethernet port. Some may have Bluetooth for extra connections.
Well, you can get a little attachment for it, which makes it run on 3G
