Mozilla add on for measuring the Elements of WebPages

About what the article is?
We are going to measure the web pages using Mozilla add on. You may ask What is the use?. This trick will helpful for website owners to fix the elements in their websites. You can measure websites for reference also.

What you need to do?
Go to this link:
https://addons.mozilla.org/en-US/firefox/addon/539/Install the Add on(by clicking the "add to Firefox" button)