Para Phenylene Di Amine is a chemical compound with the systematic name 1,4-benzenediamine. It is an aromatic compound that contains of a benzene ring with two amino groups (-NH2) attached to the para positions (positions 1 and 4) on the ring. This chemical has various industrial applications, the most common of which is its use in hair dyes and colorants. It is known for its ability to create long-lasting and vibrant colors in hair, mainly in dark shades. PPD-containing hair dyes are used to change or enhance the color of hair, and they work by forming colored compounds when they react with hydrogen peroxide. However, it's important to note that PPD can be a potential allergen and can cause skin sensitization in some individuals.