Printscreen is a Windows built-in feature provided in all most popular operating systems, including Windows 10.

To take a quick screenshot of the current screen, use the short cut key combination:

ALT + PrtScr

In modern keyboards, PrtScr key might be shared with another key such as F11, in that case, you have to use the Fn the key along with it. So, your Printscreen shortcut would become:

Fn + ALT + PrtScr

Once triggered, the captured image will be available in the Windows clipboard. You may paste it in an image editor(paint) or document editor.