The Alliance to Restore Freedom to the Galaxy (also known as the Rebel Alliance and, informally, as the Rebellion), was a loose alliance of planetary-, system-, and sector-level forces formed in direct military opposition to the Sith-Rakatan Empire. It was formed from the remnants of the Galactic Alliance by some survivors of the Jedi Order and the Imperial Knights before they were completely destroyed.
Their main aim was to overthrow the Empire and restore democracy in the galaxy. Their initial strategy was to slowly increase in strength while remaining completely hidden until they were strong enough to rise against the Empire. Although it was meant to strike against the Empire at some time, the Rebel Alliance remained hidden for well over half a century until some of its members started to loose hope in its success and the Alliance started to fall apart.