Underberg is a digestif bitter produced in Germany by Underberg AG, made of aromatic herbs from 43 countries. The exact number and identity of the herbs remain a well-guarded secret. It is based on a secret and proprietary recipe, guarded by the Underberg family since the company was founded by Hubert Underberg-Albrecht in 1846. The herbs are distilled using a process called semper idem (or "always the same"). The extracts are then matured for months in barrels made of Slovenian oak.