An extension is a small programs that add new features to your browser and personalize your browsing experience.
(definition from Google help)
5th place goes to avast! WebRep
Avast! WebRep is a extension that is a splash Screen of Avast that shows you the rating of the website. Green being safe, amber being could be dangerous and red being dangerous Avast! WebRep can be installed when any version of avast is installed on your computer.
4th place goes to DoNotTrackMe
DoNotTrackMe is a extension that completely blocks websites from installing cookies on your computer by placing a “wall” between you and the online data hoarders. By installing DoNotTrackMe the advertiser opt-out cookies are removed from your computer before they are even installed.
To download DoNotTrackMe head over to this link
3rd place goes to Hover Zoom
Hover Zoom is an extension that allows you to zoom into a photo without clicking on the photo itself. Hover Zoom works on almost every website. After installing Hover Zoom, simply place the mouse arrow over the photo to zoom.
To download Hover Zoom head over to this link
2nd place goes to Google Dictionary (by Google)
Google Dictionary (by Google) is an extension that defines a word on any website. After you install Google Dictionary, to use it simply select a word and press the Google Dictionary (by Google) button (top right) and the definition will appear.
To download Google Dictionary (by Google) head over to this link
1st place goes to Readability
Readability is an extension that works just like reader on ios. when Readability is enabled all sidebars, adverts, links, ect is removed from a page allowing just the text to be displayed thus giving the user a page that is easy to read.
To download Readability head over to this link