The history of kombucha is hazy and speculative. This intriguing fermented tea is believed to have come from China and migrated to eastern Russia. From there it migrated back to the far east and across the Pacific to the United States. My initial interest in kombucha came from it's mysterious appearance, a large brown vat of bubbling elixir with a large whitish gelatinous cap floating on top. The name kombucha is actually Japanese for "seaweed tea," because the fermenting "mother" floating on top resembles seaweed or a sort of jellyfish. The Japanese do make a tea (actually a tisane) of kombu seaweed which has the same name, but the fermented tea beverage is called kocha kinoko. In Russia it is called grib, and in China it is called hongcha jun.
Folklore surrounding the drink claim it is a health tonic with many healing properties, though this has not been extensively demonstrated by testing. The main claim for this seems to be the presence of glucuronic acid, which is a compound used in the liver for detoxification. This drink received widespread notoriety last year when a national recall pulled the emerging product ($300 million in retail sales) from retail store shelves. It had been discovered that the unpasteurized product contained more than the legal limit of 0.5% alcohol. For more on the story, read this. However, many people who are drawn to the notion of its healing properties claim that the "living" beverage loses many of its magical properties if it is pasteurized.
Returning to my original interest in the wonder drink, I was fascinated by the thick layer of SCOBY (symbiotic colony of bacteria and yeast) floating on top. This is the same thing you see in raw apple cider vinegar, but it is far thicker, and while living, it always floats. This is the perfect environment for the aerobic bacteria developing on the top of the SCOBY, and the anaerobic bacteria bubbling away from the bottom. Maintaining the pH of the fermentation is critical. Below 2.5 it is too acidic to drink, and above 4.6, it is at risk of contamination by unwanted bacteria and mold. If your grandmother ever made you drink a tablespoon of apple cider vinegar before dinner, you might be interested in trying a more flavorful alternative to healthy digestion. Others just like the taste of a slightly effervescent tea.