Adjustment Layers permit you to make non-destructive colour adjustments, but what if you want to isolate those adjustments to a particular area of the image, maybe a friends hair, your pet's collar, the sky, the ground - or some raspberry jelly? Well then you have masks, a relatively easy but hugely powerful method of applying your adjustments where you want them. In this video I'll show you how they work, and we'll set about isolating the aforementioned jelly!