Kombucha is a fermented tea made by combining a Mad Millie Kombucha Scoby (Symbiotic Culture of Bacteria and Yeast) with sweetened tea.
It has vinegary/earthy/tangy notes to it which will change and develop as fermentation takes place. The flavour can be influenced depending on your second ferment process.
See our How to Guide for Kombucha for how to make your own.