Well, Each game is different. For instance, right now Pokemon Diamind / Pearl are the most played games using the Wifi- connection. Wifi is wireless internet usually from your modem. I went to best buy and got myself a nice cheap one. For your wifi experience, you will need to give your "Code" for instance for pokemon Diamond/pearl, It is a 3 4digit code. ex. 1236-4564-1122 If that is your code, you will need to give that code to someone, and they will need to give their code to you. Once you both have eachothers codes. you will be able to Trade/battle/ chat through the DS. all those functions are only through Pokemon Diamond. Other games have Wifi, but the best one atm is pokemon. I'd say more but I have to go =) hope I helped.