How does internet work on iPhone 4S?

Can you get internet anywhere you are if you have bars? What's the correlation between megabites and internet?

I'm asking because I thought you didn't need to be somewhere with Wi-Fi to get internet on your phone but my cousin has an iPhone and last year when came to our house our internet wasn't working and he couldn't use it on his phone.

What's a data plan?

Added (1). How would that work if i'm with telus?

To use internet on a phone without Wi-Fi means you are using internet provided by a service carrier such as T Mobile, Verizon Wireless, Sprint, Metro PCS, etc. To use their internet though you must pay monthly for a "data plan"

A data plan controls how much internet your allowed monthly depending on how much you pay for.

MB and GB is related to internet because thats the system used of measuring your internet. A data plan consists of a certain amount of GB's of Internet. Its also what your paying for, the more GB of Data (Internet) the more money you pay.

Be careful though, going over a DATA plan means you get charged for that extra internet usage. And it isn't cheap. Some companys will let you out of the overcharge if you change your monthly data plan and pay more monthly for more data.Either way they make their money.