https://en.wikipedia.org/wiki/Firefox

"Mozilla Firefox (known simply as Firefox) is a free and open-source web browser developed for Windows, OS X, and Linux, with a mobile version for Android, by the Mozilla Foundation and its subsidiary, the Mozilla Corporation. Firefox uses the Gecko layout engine to render web pages, which implements current and anticipated web standards.

As of February 2015, Firefox has between 12% and 20% of worldwide usage as a "desktop" browser, making it, per different sources, the third most popular web browser. Still, the browser is most popular in several countries (as a desktop browser or even across all platforms) including Indonesia, Iran, and Germany, at 50%, 39%, and 43% of the market share, respectively.

According to Mozilla, as of December 2014, Firefox counts half a billion users around the world."

https://en.wikipedia.org/wiki/Firefox#Branding_and_visual_identity

"The animal shown in the logo is a stylized fox, although "firefox" is usually a common name for the red panda. The panda, according to Hicks, "didn't really conjure up the right imagery" and wasn't widely known. Mozilla chose the logo to make an impression while not shouting out with overdone artwork. It had to stand out in the user's mind, be easy for others to remember, and stand out without causing too much distraction when seen among other icons."

Official website