Chaoism is a belief around the idea that reality is mutable, particularly by humans. Under this system, perception shapes reality, and instinctive attachment to consensus reality prevents us from realization of the true underlying form. This is termed the psychic censor. The goal of the Chaoist is to break free of reality and reshape it to suit their own desires, usually through the use of ordeal, meditation, drugs, sex, or whatever else works. This last part is what usually defines the Chaote. Method of attack varies, but tends to involve heavy use of sigils, Lovecraftian magic, rebellion against society, and reality hacking.
Origins of the modern Chaoist movement (insomuch as there is a movement) are generally agreed to have begun with Peter J. Carroll, who in turn, borrowed heavily from Austin Spare and Aleister Crowley, who in turn stole everything from Asia, Europe, Africa, and the Middle East that wasn't nailed down. PJC went on to found the Illuminates of Thanateros, write two books attempting to found a more cohesive (hah) religious order, and has spent the last several years writing the occasional essay about the coming of the next paradigm, Aeon, or revolution.
The belief is something of a gleeful kitchen sink philosophy, which is an appropriate nod to the Thelemic origins. Much like the teenage fans of the Matrix circa the early 2000s, most Chaotes tend to go in for the black trenchcoat and candle aesthetic on the theory that if it seems badass and has a great techno soundtrack, it's probably worth wearing for a week or two.
The Chaoistic practice has very few essential cores, most of it having been gratuitously stolen by the practitioners as they saw fit. The basic practices involve ecstatic practice in various forms, sigil work, egregores, and a nigh-schizophrenic ability to accept and discard multiple views of reality, often all at once. Many Chaoists treat this as something akin to occult LARPing.
Meanwhile, Chaoism itself has been merrily percolating onwards in various forms, most of them via the Internet. Due to the anarchic nature of the "religion", such as it is, the devotees tend to either enter via Satanism, fascination with Lovecraftian entities, Wicca, or by picking up PJC's books or Spare's essays on a whim. One such example, prior to implosion, was choronzon.com, which seems to have been a heavy influence on what passes for chaoist circles on the Internet. Essays, ritual forms, and journals indicate a strong bent towards the use of entheogenic substances in order to birth/experience new paradigms. Others practice BDSM, use ecstatic dance as a medium, or pursue the contemplation of nothing, as in some forms of Buddhism.