Mac computer (Imac)
   I don't have an Imac myself so I don't have a manual for it 
       be able to create Mac OS.
         https://www.macmiep.nl/
    A Mac computer is very useful .
       And it has many key combinations like this:
        Cmd + Ctrl + Shift + 4. Copy with this combination
         you a screenshot to the clipboard.
        This is another file from the webpage seniorweb   .