Screenshots are very helpful for troubleshooting or explaining things. Methods 1 and 3 will work with most versions of Windows but 2 just on the more recent.
1. The Old method
First way is the classic PrtScn key. Press it anywhere and the screenshot of current window is saved in the clipboard. Want to save it in file? It will take some extra clicks. Open paint (or any other image editing app) and hit CTRL+V.
2. Keyboard shortcut “Windows key + PrtScn key”