Photoshop Image Masking Service is mostly used for creating product catalogs. Photoshop Image Masking is used with Clipping Path technique to knockout the background of complex image to be placed for advertisement display in e-commerce website or photo manipulation. Photoshop Masking is further useful when clipping path alone is not applicable on hair, fur, or semi transparent or translucent images like glasses, feathers, smoke, flames, highlights, lighting, chiffon & muslin, etc.
Masking an image enables a developer to create images with irregular shapes dynamically. Masking is often used to create a user interface that is more compelling and less boring.
There are two types of masks: layer mask which is pixel depended (described above) and vector mask which is a path that clips out the contents of the layer and is pixel independent. It is much easier to edit vector mask by the way using path anchor points.