Data plan - what does this mean?
 

I'm new to smartphones and still have a basic mobile phone. I saw this listed as one of the options for a data plan, but what does it mean exactly?

"$30/mo* - Cost Assure for PDA Data Add On"
"* Rate Adjusts automatically based on actual usage."

I interpret it as, pay for what you use, basically. So if I check 1 email, I'll get a charge for 50kb or whatever.

Please help :)

It means if you go over you will be charged more.

thanks!