The generic image file that most cameras create is called a JPEG. A JPEG is just a very simple file that has the exact exposure as recorded by your camera embedded with your metadata in the image.
All computers can process JPEGs and can open JPEGs. It's the standard for images on the internet. It's really nice to have just one basic file format that everything can read. It works with everything, every piece of technology.
Higher end cameras will allow you to save in other file formats like RAW, which is just a higher quality, larger file than a JPEG image and contains much more data. However, JPEG, on most cameras you can adjust the size of your JPEG image from something like fine to basic. What that really controls is just how much detail there is in that photo. For most people, basic is generally OK. But if you're looking to blow up your images larger, I would always go for the largest file size. It just gives you more to work with and more resolution.
The nice thing about JPEG files is they are the standard for all imaging files, whether it's on the internet, in e-mail, or just viewing them on your computer. All pieces of technology can read JPEGs and all cameras have the ability to save in JPEG.
That's everything you need to know about JPEGs.