As the name suggests, masks hide or show parts of an object or image. You can use several masking techniques to achieve many kinds of creative effects with objects.

You can create a mask that acts as a cookie cutter, cropping or clipping underlying objects or images. Or you can create a mask that gives the effect of a foggy window, revealing or hiding portions of the objects beneath it. This type of mask uses grayscale to make selected objects less visible or more so. Or you can create a mask that uses its own transparency to affect visibility.

You can create a mask using the Layers panel or the Edit, Select, or Modify menus. After you create a mask, you can adjust the position of the masked selection on the canvas or modify the appearance of a mask by editing the mask object. You can also apply transformations to the mask as a whole or to the components of a mask individually.