Image masking is a process of hiding some portions of an image while revealing other by using Photoshop masking and pen tools. This technique is commonly used for removing a person or an object from the image. Also, it lets you to adjust and re-edit the mask of your images afterwards if necessary. We mainly use this technique when the subject is fur, smoke, human hair, cotton, glass, feathers, tree, flames etc.There are many categories of masking. For example: layer masking, channel masking or alpha masking, clipping masking, transparent masking, hair masking, refine edge masking, color masking etc.