A paraben is a member of the ester family of organic chemicals that form when organic acids and alcohols react. Manufacturers use parabens as preservatives in cosmetics to improve their shelf life and to reduce the growth of bacteria in them.
Parabens are of interest because of a 2004 research study reporting parabens found in breast tumors. The Food and Drug Administration responded to the article stating there was no reason for the public to be concerned about these chemicals. The concern over the potential danger of parabens led to the development of several cosmetic lines that do not use these preservatives. These cosmetics are labeled as paraben-free.