Tanbark is the bark of certain species of tree. It is traditionally used for tanning hides.

The words "tanning", "tan," and "tawny" are derived from the Medieval Latin tannare, "to convert into leather."

Bark mills are horse- or oxen-driven or water powered edge mills and were used in earlier times to shred the tanbark to derive tannins for the leather industry.

A "barker" was a person who stripped bark from trees to supply bark mills.

Tanbark around the world

In some areas of the United States, such as northern California, tanbark is often called "mulch," even by manufacturers and distributors. In these areas, the word "mulch" may refer to peat moss or to very fine tanbark. In California, Lithocarpus densiflorus (commonly known as the tanoak or tanbark-oak) was used. In New York, on the slopes of Mount Tremper, hemlock bark was a major source of tanbark during the 19th century.

In America, condensed tannins are also present in the bark of blackjack oak (Quercus marilandica').

Around the Mediterranean Sea, sumach (Rhus coriaria) leaves and bark are used.