Pale Moon is an Open Source, Goanna-based web browser focusing on efficiency and customization. It's completely built from its own, independently developed source that has been forked off from Firefox/Mozilla code a number of years ago, and focuses on efficiency and ease of use by carefully selecting features and optimizations to improve the browser's stability and user experience, while offering full customization and a growing collection of extensions and themes to make the browser truly your own.
This browser, even though fairly close to Gecko-based browsers like Mozilla Firefox and SeaMonkey in the way it works, is based on a different layout engine and offers a different set of features. It aims to provide close adherence to official web standards and specifications in its implementation (with minimal compromise). With the current generation of mainstream browsers, there are also more obvious and not just "under the hood" differences: Pale Moon will continue to provide grouped navigation buttons of a decent size, a bookmarks toolbar that is enabled by default, tabs next to page content by default (easily switchable) and not in the least a functional status bar and more freedom in customization. Pale Moon is specifically optimized for current-day processors and as such requires a reasonably modern system to run properly.
Pale Moon for Linux is distributed as a bzipped tarball that can be extracted and run from any location on your system. Be sure to download the correct archive that matches the architecture of your OS. To use, simply extract the tarball anywhere you like and execute the "palemoon" file inside it. It is recommended that you extract Pale Moon to a user-writable location so that the internal updater can work as intended to keep your browser up to date.