A kombucha SCOBY (also known by some as the kombucha mother or mushroom) is used in the process of brewing kombucha tea. SCOBY is an acronym standing for symbiotic colony of bacteria and yeast.
Kombucha is created by fermenting tea with sugar and the SCOBY. After enough time, you have delicious kombucha tea to enjoy. The longer you leave the kombucha unrefrigerated, the more it can ferment and change in flavour, which you can experiment with to find what suits your tastes. Placing your kombucha in the fridge puts it in a dormant state, where the cold will halt or slow the fermentation process.