A mask is a vector path which allows part of an object
to show while blocking out the rest effectively making
part of it transparent. A mask in an illustration program
is functionally equivalent to a clipping
path in an image editor (more).
1. Take for example a photo. You can create a mask which
will knockout the background.
2. Using the Pen, draw a path around the bird in the
photo.
3. This is a view of the path only.
4. When the path is made into a mask and combined with
the background image, the background becomes transparent.
5. Masks can be made to create many kinds of effects.
A type mask can be combined with a background photo.
6. This is the mask created by converting type to curves.
7. This is the type mask when combined with the background
image.
