Firefox add-ons vs. Themes

# of extensions over time

Add-ons: Boost browser functionality

Add-ons extend the functionality of the browser and the websites being viewed in it. They are usually in effect across all websites (though some are site-specific).

Themes: Customize browser appearance

Themes personalize the appearance of the browser by changing the color scheme and background. Themes also change the appearance of everything from the tabs to the scrollbar. However, unlike extensions, changing a theme does not change how the browser works.

Break down by type
Number of extensions in each type
Chart
Table
Add-on 29,651
Theme 487,662