What is LTE on AT&T iPhone 5?

Is it on every iPhone 5 for AT&T? I want to get the iPhone but I'm not sure what that it. And how much internet and stuff like that can I use if I just get the cheapest data plan for AT&T? I'm not like a Facebook/Twitter/Instagram addict but I do use Internet. Will it also count for the Maps and when I go to the iTunes store/App store?

LTE is 4G network support.speed in 4G network is 100 mbps. And that depends on the locality you are staying