ISO forms part of the exposure triangle. We'll be looking at the exposure triangle in a later tutorial. Where we put together ISO, Shutter Speed, and Aperture. In this tutorial, we will look at ISO as an individual element.
Look up RAW v Jpeg on the internet or YouTube, and there are as many opinions about the subject as any political issue. It's one of photography's great debates. So why shouldn't I put in my two pennies worth?