There are often times, especially when I’m trying to convey a technical issue I’m having with my computer, when it’s much easier to show the problem than to spend paragraphs trying to explain it. Both Macs and PCs have had the ability to take screen shots (or screen captures) since time immemorial, and it’s a simple and useful task for capturing a problem visually. Screen shots are also useful for creating how-to documentation or to complement a review or other article about a piece of software, for example. Here’s a primer on how to take screen shots on your computer in case you have to capture what’s on your screen at a given time.

Macs

• To capture the entire screen: Shift+Command+3
• To capture a selected portion of the screen: Shift+Command+4 turns your mouse cursor into a cross hair. Drag a rectangle around the portion of the screen you want to capture.
• To capture a window: Shift+Command+4 again turns your mouse cursor into a crosshair. Then press the spacebar, which turns your cursor into a camera icon. Place the camera icon over the window you wish to capture (the selected window will highlight in blue) and then click. Even if the window you’re capturing is partially obscured by another window on top of it, your screen capture will be of the entire unobscured window.

In each case, you’ll hear a camera shutter sound to let you know the screen capture worked. The images you capture will be saved to your Mac’s desktop. On Mac OS 10.6 Snow Leopard, the file is saved as a PNG and named as “Screen shot” followed by the date and time you took the shot. Earlier versions of Mac OS X name screenshots as Picture 1, Picture 2, etc., and save them as either PNGs or PDFs.

Windows

• To capture the entire screen: press the Print Screen button (possibly labeled PrtScn or something similar, depending on your keyboard). This copies the entire screen onto your computer’s clipboard.
• To capture the active (frontmost) window: press Alt+Print Screen. Again, this copies the selected window to your computer’s clipboard.

Unlike the Mac, there is no audible feedback when you perform a screen capture on Windows, and instead of saving the screen capture as a file, Windows only copies the image to your clipboard. You’ll then have to open an image editing program, such as Microsoft Paint, and click the Paste button to paste your screen capture into the document, where you can then edit it before you save it, if you like.

Mac OS X also includes an application called Grab, located in your Applications > Utilities folder, which gives you slightly better controls over the portion of the screen you’re capturing. It also offers a “Timed Screen” option which gives you 10 seconds to get your screen ready before it takes the shot. This can be useful if you need to capture something in action and don’t have your hands free to manually perform the screen capture.

Windows Vista and Windows 7 both include an application called Snipping Tool, located in All Programs > Accessories, and it, too, gives you more and better options for creating screen captures, including the ability to grab irregular shapes and specific portions of the screen.

So if you’ve never taken screen shots before, take some time and play around with the different controls and options. You may be surprised at how often screen captures come in handy.

See the accompanying video for additional screen shot controls.