There are many misconceptions out there about what the Golden Dawn is. Instead of disputing or debunking them, let us look at what the Golden Dawn really is. These points are in no particular order, nor are they a complete representation, but they will hopefully shed more light on this more than a century old tradition.
The Golden Dawn is a syncretic tradition that combines and unifies a multitude of magical systems employed in the Western Mystery Tradition, including, but not limited to: Qabalah, Astrology, Tarot, Hermeticism, Alchemy, Rosicrucianism, Enochian, Geomancy, and various other esoteric subjects.
The Golden Dawn is a school that teaches a structured approach to magic, being primarily theoretical in the Outer Order (the Golden Dawn proper) and practical in the Inner Order (the RR et AC or Rosae Rubeae et Aureae Crucis). Some have likened the requirements of Golden Dawn study to that of a college degree, with several grade exams and a thesis of several thousand words required in the Portal grade.
The Golden Dawn is a magical order dedicated to the aim of creating magicians and adepts, who are "more than human" and dedicated to the Great Work. Magical techniques are taught and employed for multiple ends. Depending on the group in question this might be entirely spiritually focused or a mix of spiritual and practical. Members usually practice magic on their own and as part of their temple.
The Golden Dawn is a system of alchemical change that, if properly adhered to, highlights the imbalances within us and forces us to address them. It works as a form of active therapy, where we work out our problems so that we can become better people, both in a mundane and spiritual sense. We are torn apart that we may be renewed. Our old self, created by societal imprints and pressures, is replaced with a new self that we alone create, one that is no longer bound by illusion and limitations, where we actively engage with our life and where we want to lead it, and take responsibility for all that we think, say, and do.
The Golden Dawn is a fraternal group that is open to a wide mix of people from all backgrounds. It was one of the first magical groups to accept women, despite its Masonic background, and it has included members of multiple religions, teaching that there is value in all of them. This fraternity has expanded in modern days, with most groups being open to members of any gender, religion, nationality, ethnicity, sexual orientation, disability, or political persuasion. Most modern Golden Dawn groups extend their fraternal relations beyond just their own group, encouraging a growing and thriving exchange between members of various Orders and those who belong to independent temples or work on their own.
The Golden Dawn is a "Society of Kabbalists," according to the original publicity of its existence (see this post by Olen Rush). This emphasises the important place of the Qabalah in the Golden Dawn, and many people see it as the underlying tradition that interweaves the entire system of magic.
The Golden Dawn is a 19th Century creation based on earlier teachings and traditions. The Cipher Manuscripts upon which the Outer Order rituals and Knowledge Lectures are based are widely believed to be the work of Kenneth Mackenzie (1833-1866). The Order itself opened in 1888. Westcott's official "History Lecture" proposes a fanciful history that links the Order back to ancient times, but historical evidence and common sense contradicts this. This in no way invalidates the Order or its teachings, however, which are certainly rooted in older tradition.
The Golden Dawn is one of many equally valid magical traditions. The Order popularised many occult topics and contributed a significant amount of material to the modern approach to magic, but it is only one of a large consortium of groups that has influenced the wider Western Mystery Tradition. While many present-day magicians owe some of their knowledge to the Golden Dawn, the Golden Dawn owes much of its knowledge to older traditions and magicians who came before it.
The Golden Dawn is a living, breathing and growing tradition. Over the years the Order has been maligned by some from without and within, but it is as strong as it has ever been, with more members today than at any time in its history. Some have suggested it is obsolete, but it still provides the tools for change that many magicians find are powerful and valuable. Many Order papers remain unpublished, some are only recently being shared with the wider world, and modern adepts are contributing new material, just as the adepts of the original order did. There has never been a better time to be a member, whether it is within an order or as a solitary magician.