Why is the tongue of some people brown?

A brown tongue can result from several factors, including poor oral hygiene, which allows bacteria and dead cells to accumulate on the tongue's surface. It may also be caused by certain medications, tobacco use, or dehydrated conditions, leading to a buildup of a substance called keratin. Additionally, dietary choices, particularly those high in certain pigments or spices, can contribute to discoloration. In most cases, maintaining proper oral hygiene can help resolve the issue.