If I have 4g turned on will that count as using Internet or until I open a web page?

I just got an iphone 5 and I don't want to get charged for no reason so I'm confused on this, if 4g is on and let's say I'm not using my phone and its just in my pocket will I be charged?
Will I be charged until I use the Internet/app?
Because I get pictures from friends randomly and you can only receive if you have 4g/lte or Wi-Fi on so is it safe to say that I won't get charged for just having 4g on when I'm out?

I don, t think you, ll be charged for iphone in your pocket or taking pictur, etc.you, ll be charged for subscription fee and use of internet. Good deed.

You don't get charged till u actually use your 4g so if your 4g is on and it's in your pocket and for example u receive a Facebook notification then you will be charged because it used the Internet or 4g