Google Chrome offers several ways in which other programs can change its behavior and improve its features. The add-ons are software programs that extend the capabilities of the browser in a specific way - giving you, for example, the ability to play audio samples or view video movies from within your browser.
The Google Chrome Add-Ons tool allows you to activate/deactivate or install any extension.
When an add-on is active, a blue checkmark is present in the circle to its left. Also, on the right section you will see a green dot and the word "active". To make it inactive, simply click the circle so the checkmark disappears. On the right you will see a red dot and the word "inactive". To delete an add-on, hover over it and then click the red trash can button.