Mask Explanation

[MahaB82A]

The meaning for Mask in Cambridge dictionary is FACE COVER. But in Pr if a shape or text is in a mask only it is visible. Why is it called Mask?  

[Warren Heaton]

Hi @MahaB82A:

It looks like you've posted this same topic in more than one Adobe Community forum.  

Here's a link to the other thread for those that might be interested in the topic:
After Effects > Discussions > Re: Mask in Ae

[MahaB82A]

Thanks for let me knowing it.