IMessage use data? How much?

Ok so I just got an iPhone 5c and I'm a little confused now. I heard that you can basically only use iMessage to text other iPhone, iPod ect. Users. But then I heard that using iMessage uses data. I have 4 GB and I'm just wondering if I text kind of a lot using iMessage if it would kill my data? Obviously I'm not really good with this kind of stuff so any info you have to help me would be great

You heard incorrectly. IMessage can be used to text other iMessage users AND other SMS text, non-iMessage users. We don't know how much texting you do + any other data use (video, email, social media sites, etc), but texting (including iMessage) does not use much.

YES IT USES DATA BUT NOT MUCH AND YOUR CHARGES WILL DEPEND ON YOUR CARRIER BUT I KNOW IT DOES COST MUCH

IMessage uses data but it's a trivially small amount. You could literally send several million texts via iMessage without running out of data.

iMessage does not use SMS. If you text a non-Apple device, the text is sent via a regular SMS directly through the phone in your device. If you have an iPad, you can't send SMS texts at all, since it doesn't contain a phone.

IMessage is not a text service, its an instant message service, hence why it uses data (if not on a Wi-Fi connection) in order to operate. It depends on how often you use iMessage, but assuming you only send messages (with no media) it would take a while to knock out 4GB of data

Very small amount of data, I wouldn't even worry about it unless you are constantly attaching pics or videos.