Sorry that was just in the list of what I would need to buy if I were to build a computer. That's to hook a desktop up to a wireless network. I don't feel like running an ethernet cable from the router to my room, so it's just so I can get internet wherever I put the desktop. Right now there's only one desktop in the house, so the router is just wired to that and the laptops work off wireless.
If that made any sense at all..
How do you plan on connecting to the internet if you would build a new pc? Do you already have multiple in the house? If you don't have a router already that will add $100 for the desktop adapter (the part in question) and the actual router.
I'm not good at explaining things.. basically just ignore that for now, you may end up needing something like it though, but you can figure that out after the pc is built.