Ouzo is a dry anise-flavoured aperitif that is widely consumed in Greece and Cyprus. It is made from rectified spirits that have undergone a process of distillation and flavoring. Its taste is similar to other anise liquors like rakı, arak, pastis and sambuca.

Ouzo has its roots in tsipouro (brandy from Greece), which is said to have been the work of a group of 14th-century monks on Mount Athos. One version of it was flavoured with anise. This version eventually came to be called ouzo.

More Info: en.wikipedia.org