To share your Internet connection between two or more computers — as well as to share files, printers and other devices, if you like — you need to connect them (and your modem) on a home network. About the easiest and least complicated way to do this is with a router. Furthermore, a WiFi router will enable your laptop (and other WiFi equipped devices) to connect to that network wirelessly. I’ve written a few articles about computer networks for non-technical people:
