Does the IPhone 4 apps use data or Wi-Fi?

Does the IPhone 4 apps use data or Wi-Fi?

Well, if you're connected to Wi-Fi, it uses your Wi-Fi. If your're not connected to Wi-Fi, it'll use data.

Both: when you are connected to a network on Wi-Fi then it will use the internet on that network but if you are on the bus or whatever then you are using data… You can also choose to make your phone into a hotspot which is basically what makes a Wi-Fi signal so that other devices can use the internet when they use your signal… The downside is it wastes alot of data if you decide to do that