What uses data on an iPhone 5c?

So I'm supposed to be getting a new phone. And I was trying to figure out how much it costs monthly. And I wasn't sure how much data to buy. So I used a data calculator but it wasn't the most helpful for me because I didn't really understand it that much. Like for example when it says streaming music, does that mean just playing music from the music app? Does that take up data? Because that's kind of ridiculous in my opinion… But anyways my point is I don't know what to say for the questions and all. I have about 450 songs on my iPod right now. If I out all these songs on my new phone will that take up data? How do I know how much data I should buy? I want to keep my cost as low as possible, but I want to make sure I will be able to use the phone for the purposes I need it. And so that it'll make sense of having it. You know? I'm pretty sure I get unlimited calls and texts. Which isn't really what in worried about. That's a good thing because I need the unlimited calls and texts. But what takes up data? How do I know what amount to buy. My mom is going to try and turn it off completely I believe for some reason, but I need to know if like I have to have it on to use the phone and what amount to buy. Thanks for the help.

Added (1). Our carrier is Verizon by the way. I know different places give you different amounts of data for different prices

Almost every app will use data unless you tell it not to. Settings-General-Usage.

I don't believe there are any carriers that will permit you to have an iPhone without a data plan. Data charges are a lucrative, money-making source for carriers. Therefore, it is a good idea to estimate your data usage as you are trying to do. Note that you will not use any data while your iPhone is connected to Wi-Fi. The following applies during those times when you are not on Wi-Fi.

Streaming from a music app, like iTunes Radio, Pandora, and Spotify uses data. Playing music that has already been downloaded into your iPhone from a computer does not.

But there are gotchas. If you buy a song from the iTunes store app on the iPhone, then it will use data to download it to your iPhone. If you buy a song from the iTunes store on the computer AND your iPhone is set up to automatically download all songs, then that will use data, too. If your iPhone is set up to not automatically download songs, you can still manually download them from the Music app; this will use data. All of these cases are considered Audio Track Downloads on Verizon's Data Calculator.

Hopefully, this answers your questions about music-related data charges and gives you a better idea about which data plan to purchase. You should definitely make sure to get more than you need. The surcharges for exceeding the limit are very high. If you find that you are using much less data than you need, you can always switch to a cheaper data plan.