**2.3. Classification based on distribution in nature**

Based on their extent of distribution in nature, phenolic compounds have been classified as being shortly distributed, widely distributed and as polymers. Widely distributed phenols are the types that are present or available in all plants, or are of high significance in specific plants. Examples include flavonoids and/or flavonoid derivatives, coumarins, phenolic acid including benzoic acid and cinnamic acid. Those that are shortly or less widely distributed are limited and include simple phenols, pyrocatechol, hydroquinone and resorcinol. Examples of the polymer class of phenolic compounds are tannin and lignin [9].
