In Photoshop CS versions, selections can be stored as a Channel, known as ‘Alpha Channels’
Once you make a selection using a tool such as the Quick Selection, Ctrl/right-click and choose Save Selection from the list of options.
This opens up the Save Selection dialog box, where you can give the selection a name. Set as New Channel, hit OK to store the area to use anytime.
This saves the selection inside the Channels palette as an Alpha Channel (a black and white layer).
Click on the Channel to view it as a mask, or Cmd/Ctrl-click on it’s thumbnail to load the selection back up.