What will use my data on iPhone?

What will use my data? I'm getting an iPhone soon. How much data is 1 gb? Will these apps waste my data: Subway Surfer, Facebook, and Twitter. I know FB and Twitter will when I'm outside Wi-Fi, but will Subway Surfer waste my data?

Yes all of them will, but not to worry 1GB is a lot of data so you might find your self not even using have it in a month. In estimation a normal browse of Facebook is like maybe 10MB which > 10 - 15 mins probably.

Anything involving internet access & done using 3G/4G will use data.