1. Command + Shift + 4: Screenshot
    Screenshots get me through the day. Screenshots fill up my desktop and I don't know what I would do without this shortcut.
  2. Command + F: Search
    No one has time to read a whole web page anymore.
  3. Command + C: Copy
    Basically I'm just too lazy to type out a sentence I've already written somewhere else on my computer.
  4. Command + Z: Undo
    The "I did not mean to do that" shortcut. It's a lifesaver.