Many people are unaware of the fact that their Mac actually has a built-in digital camera for taking screenshots and screen grabs.  It really is a magical little tool and deserves to be noticed! It's very simple to use really.  Just press the CMD and SHIFT modifier keys at the same time and while you are still pressing them, press the number 3 on the top row of keys (not from the keypad if you have one).  You will hear a click like the shutter of a camera and the next thing you know - there's an image file on your desktop which contains a full screenshot of exactly how your screen was when you pressed the '3' key.  This can be very useful in many situations, such as sending in a screenshot to help diagnose some Mac problem that you are experiencing. Furthermore, bigger and better in my view, is the screen grab feature.  In exactly the same way, you press the CMD and SHIFT modifier keys at the same time - but this time you press the number 4 from the top row of keys.  A small cross-hairs will replace the arrow on the screen and you can then draw a box around whatever it is you want to grab.  As soon as you let go of the mouse button, you will hear the camera click sound and another image will appear on your desktop.  This time it contains only the area you selected on the screen. Now that you know about this little trick and you know how to use it, I bet it comes in very handy on a regular basi 🙂