6 formatting fixes, removed redundant parts
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For devices still running Windows Phone 8, Holdhold the power button and then press the Windows key to take a screenshot on a Windows Phone 8 device. The screenshot will then be stored intoin a Screenshots"Screenshots" album in the photos.

For those updated to Windows Phone 8.1, press and hold power+volume up simultaneously.

There is a video guide from Microsoft on YouTube

For devices still running Windows Phone 8, Hold the power button and then press the Windows key to take a screenshot on a Windows Phone 8 device. The screenshot will then be stored into a Screenshots album in the photos.

For those updated to Windows Phone 8.1, press and hold power+volume up simultaneously.

There is a video guide from Microsoft on YouTube

For devices still running Windows Phone 8, hold the power button and then press the Windows key. The screenshot will then be stored in a "Screenshots" album in the photos.

For those updated to Windows Phone 8.1, press and hold power+volume up simultaneously.

There is a video guide from Microsoft on YouTube

5 embedd official video for w8, see http://meta.stackexchange.com/a/104189/237803 and request if it is not enabled
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Windows Phone 8

For devices still running Windows Phone 8, Hold the power button and then press the Windows key to take a screenshot on a Windows Phone 8 device. The screenshot will then be stored into a Screenshots album in the photos.

Windows Phone 8.1

For those updated to Windows Phone 8.1, press and hold power+volume up simultaneously.

There is a video http://www.youtube.com/watch?v=Pxi5uYX-5-Eguide from Microsoft on YouTube

Windows Phone 8

Hold the power button and then press the Windows key to take a screenshot on a Windows Phone 8 device. The screenshot will then be stored into a Screenshots album in the photos.

Windows Phone 8.1

For Windows Phone 8.1, press and hold power+volume up simultaneously.

http://www.youtube.com/watch?v=Pxi5uYX-5-E

For devices still running Windows Phone 8, Hold the power button and then press the Windows key to take a screenshot on a Windows Phone 8 device. The screenshot will then be stored into a Screenshots album in the photos.

For those updated to Windows Phone 8.1, press and hold power+volume up simultaneously.

There is a video guide from Microsoft on YouTube

4 embedd official video for w8, see http://meta.stackexchange.com/a/104189/237803 and request if it is not enabled
source | link

Windows Phone 8

Hold the power button and then press the Windows key to take a screenshot on a Windows Phone 8 device. The screenshot will then be stored into a Screenshots album in the photos.

Windows Phone 8.1

For windows phoneWindows Phone 8.1, press and hold power + volume uppower+volume up simultaneously.

The screenshot will then be stored into a "Screenshots" album in the photos.http://www.youtube.com/watch?v=Pxi5uYX-5-E

Hold the power button and then press the Windows key to take a screenshot on a Windows Phone 8 device.

For windows phone 8.1, press and hold power + volume up.

The screenshot will then be stored into a "Screenshots" album in the photos.

Windows Phone 8

Hold the power button and then press the Windows key to take a screenshot on a Windows Phone 8 device. The screenshot will then be stored into a Screenshots album in the photos.

Windows Phone 8.1

For Windows Phone 8.1, press and hold power+volume up simultaneously.

http://www.youtube.com/watch?v=Pxi5uYX-5-E

3 add desc for WP 8.1
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2 This is the top hit on google. This edit makes the answer the result.
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