So, you want to show someone something that is on your screen. Problem is: they’re not in the room. You need to take a screenshot. And that’s OK, because the Apple engineers behind OS X have provided you with a virtual smorgasbord of screenie-snapping options…

• Command-Shift-3: Takes a full-size screenshot; and saves it on the desktop.
• Command-Shift-4, then select an area: Takes a screenshot of an area; saves it on the desktop.
• Command-Shift-4, then space, then click a window: Takes a screenshot of a single window; saves on the desktop. This even includes the OS X drop shadow.
• Command-Control-Shift-3: Takes a full-size screenshot; saves it to the clipboard.
• Command-Control-Shift-4, then select an area: Takes a screenshot of an area; saves it to the clipboard.
• Command-Control-Shift-4, then space, then click a window: Takes a screenshot of a window; saves it to the clipboard. Also preserves OS X drop shadow.

Need more control? Fine: Hold down these additional keys while selecting an area via Command-Shift-4 or Command-Control-Shift-4 and you get even more functionality…

• Space: Locks the size of the selected region and move it when the mouse moves.
• Shift: Resize one edge of the selected region.
• Option: Resize the selected region with its center as an anchor point.

…And now you have a portable version of exactly what you see.