Hi! :)
So, I'm not sure if any of what I'm going to say is technically accurate, but this sort of what I know based on a few things I've read:

RAW: The image size is larger (so less photos fit on your memory card), but it's the raw data, so when you open it in camera raw, you can open it to almost whatever size you want and you can mess around with it a bunch without compromising pixels and image quality. This is especially helpful if you don't always get exposure right in camera (I almost always end up adjusting exposure). So I tend to open photos in camera raw, mess with exposure and color balance and things like that, and then open them as jpgs in photoshop to crop and run actions and things like that.

JPG: I think this is what most cameras default to if you're not shooting RAW, and you can do high quality jpg files, but I think it limits what you can do, because it's a lossy file type. I think you can still play around with exposure and color balance, but messing around with it too much can start to compromise the quality of the image, because you're already starting out with a slightly compressed image.

Hopefully that kind of makes sense?

I suppose it depends on what you're doing with your photos? Just posting to the web so friends can see? Not planning on making large prints? Maybe shoot in .jpg? Taking beautiful naturey crap photos that you might want to frame and hang on your wall? Then maybe shooting RAW is a better idea?

There's an article here that probably answers it better than I have: http://digital-photography-school.com/raw-vs-jpeg

:)