document updated 15 years ago, on Jan 9, 2009

These get jumbled up in my head. A short summary of each:

Homeopathy. Diluting a harmful substance can cause it to have the inverse (beneficial) effect. The more dilute it is, the stronger its effects are. Often solutions are diluted to a few parts per million, but sometimes MUCH more than that, well below Avogadro's number.
- Homeopathy and herbal medicine are sometimes conflated for legal reasons. Homeopathic solutions, as they're usually formulated, contain "little or no active ingredients".
Chiropractic. Has origins in alternative medicine, for example, believing that defects in the spine can cause almost any disease. However, a majority of current practitioners consider themselves to be part of mainstream (rather than alternative) medicine. (i.e. they should just call themselves physical therapists and stop confusing people)

Things that are often classified as alternative medicine, but which have at least minimum credibility within the scientific community. Unlike the above, these shouldn't be treated as malicious quack science:

Acupuncture. Evidence is definitely mixed, so one must take the agnostic position on this until we know more.
Hypnosis. Mainstream science has supported it for over a century.