Add new features
Some extensions allow you to add new features to your browser. For example, the Google Mail Checker extension let‘s you know when you have new email, no matter where you are on the web.
Change how Chrome works
There are also extensions that allow you to alter Chrome's functionality. Some extensions change the look of your New Tab page, while others add new options to your right click menu and the browser's address bar. For example, the Google Tasks extension allows you to add a task directly from the omnibox.
Modify web pages
Several extensions allow you to change the look and the functionality of your favorite web pages. For example, the Favorite Doodle extension lets you replace the Google logo on the homepage with the Google Doodle you select.