Do i need a wireless router or a wireless card?

I was looking into setting up a wifi network at home for use with my kindle and maybe a nexus seven. As i was looking through some i found on amazon i realized i have no idea what im doing. I was looking at this and it mentions its for hooking up a pc to a wireless network. So do i need a wireless router?

You can use a card like the one you linked to share your connection through your computer. This would only work when your computer is turned on, so i am pretty sure you need a wireless router.