With the assumption that the term wifi means a wireless network between 2 or more computers, one only requires 3 basic components (besides the computers themselves): 2 (or more) wireless adapters and a wireless router or hub.
The adapters (assuming wireless functionality isn't built into the computers themselves) can be PCI cards, USB devices, or any one of the many possible devices currently on the market. You will need 1 wireless adapter per computer. These can be purchased at most retail electronic outlets.
The wireless router itself is usually a standalone device, purchasable at most retail electronic locations, that will provide a hub for the network as well as a gateway to other networks (such as the internet).
Exceptions:
Many WiFi devices are capable of connecting directly to each other (2 computer connecting directly via their adapters, without a router). A common example of this is handheld game consoles.
Hotspots are WiFi enabled locations in areas like coffeeshops, restaurants, etc. This means that someone with a Wifi enabled computer or device can connect to the Internet or other public network via a local wireless router. (1 computer with WiFi adapter and 1 public WiFi router)
Yes, you need wifi to FaceTime.
Yes you do need wifi
You need Wifi to do anything on YouTube.
Yes you need WiFi
You only need WiFi if you are downloading new books. Books already downloaded do not need wifi
WiFi usb adapter is a WiFi card.
No wifi
You need a wifi router or a Nintendo wifi usb
wifi connections.
you need wifi. if you have wifi then you probably cant get it and you need a different ipod
tapped out does need wifi it's very anoying
You need pay only for the adapter. If you have a wireless router you will not have to pay to anybody for your WiFi. But you still have to for Internet.