* What is a Firefox Theme?

A theme is a customization of the look and feel of the browser.

For example, a theme can change the default colours and the icons used for the buttons.

* How to get and install Firefox add-ons.

We can get Firefox add-ons from the website: https://addons.mozilla.org/

Search and choose you want.

* List and describe as many extensions/themes as you can

-Chatzilla: An IRC chat client for a community to discuss any issues.

-DOM Inspector: Inspect the DOM of HTML, XUL, and XML pages, including the mail chrome.