That old saying that "A picture is worth a thousand words" has special meaning when dealing with computer problems. Sometimes the best way to explain a problem or its solution is with a screenshot, a copy of what appears on the screen of the computer. Macintosh computers offer several ways to take a screen shot using keyboard shortcuts. In a "Pro Tip" article, Apple recommends saving "clean screenshots of individual elements on your desktop ... without capturing anything else in the background."
Press the "Command", "Shift" and "4" keys on your keyboard simultaneously.
Press the space bar on your keyboard. A small camera icon will appear.
Move the camera icon over the element you want to capture. It will appear highlighted on the screen. Press the mouse or track pad button to capture the screen shot, which will save to your desktop.