Obtaining a screenshot of a whole web page is a little bit tricky, as normally by using print screen you only capture the portion of a webpage, which is viewable on screen. Now, if you want to capture full webpage and you are using Google Chrome web browser then here is an extension that let you allow to take whole web page screenshot in a quick way without installing any third party utility.
Take Full Web Page Screenshot in Google Chrome
Visit Chrome Web store and search for “screen capture”
Click on Screen Capture (by Google) from results and install it
Screen capture icon will be added to the right side of Chrome toolbar, click on it and from the menu select the option according to your choice like capture page region, capture visible content of a web page, or the whole page
After completing process of taking screenshot, a bar will appear where you find different options like save, share, annotations etc… to the captured image
So, the screen capture by Google is a nifty extension for Google Chrome browser, that is free and works perfect to capture web pages screenshots.