To take a web page screenshots, users normally had to installed a screen capture applications such as WinSnap or Snagit into their computer. To have a good screen capture programs, you need to use a commercial one but of course you have to buy it. There are some free programs available but with a limited of functions, it does not give you any satisfactions.
Even with the best screen capture programs installed in your computer, when you're found something that interested you while browsing the website/s and want to take a screenshot, you need to launch that program, set it up and a few things has to do before you get that shots. How about just do a right click, drag and drop and save the image as easy as 1 2 3 ....
Rowan Lewis has developed an add-on for Firefox called 'Abduction!' a right click option to take screenshot of an entire web page or just part of a web page to save as an image.