1. What are raw files?
To understand raw, it helps to know how a digital camera actually produces an image.
When you fire the shutter, the image you take is recorded on your camera’s sensor, where the light is converted into an electrical signal that forms the image data.
This ‘raw’ data is what makes up the majority of a raw file. Simple so far. What happens next differentiates raw files from the JPEG image format.
The raw file is simply this image data, along with the information needed to construct the image, which is written to your memory card (find out how memory cards work).
With a JPEG, before the image is written to the card the original raw data is processed (how it’s processed depends on what camera settings you’ve chosen, eg White Balance or a specific Picture Style). The file is then converted to JPEG format and finally written to your memory card.
So, to recap: your camera produces raw files as a matter of course, but it’s up to you whether you let the camera process these for you to produce a JPEG, or whether you stick with the original raw file (check out these reasons why you want to shoot JPEG).