Knowing how to select parts of your Gimp documents with the help of Quick Mask might be one of the first things you should learn when starting with Gimp. Let me introduce you to the basics of Quick Mask.
In this simple tutorial suitable for the Gimp beginners as well, we are going to manipulate a photograph of standing still car to make it look like it's passing by real fast.
Simple yet very useful Gimp tutorial where we make a detail or an object in a Photo bigger and more visible by resizing it and adding a white rounded square frame around it.