Mozilla Firefox is a free and open source web browser developed for Microsoft Windows, OS X and Linux (including Android) coordinated by Mozilla Corporation and Mozilla Foundation. Firefox uses the Gecko layout engine to render web pages, which implements current and anticipated web standards.
Website to get latest firefox linux version:
On archlinux just install using pacman.
#pacman -S firefox
To install flash player on firefox
#pacman -S flashplugin
Firefox on archlinux, is regularly updated when the firefox get news release. Just pacman -Syu and you get the latest updates.