Parabens are very effective preservatives that prevent mold, fungus, and bacteria from growing in the product for extended amounts of time. This way, parabens greatly extend the shelf life of products, sometimes for 5-6 years. Cosmetic products today are often manufactured in very large batches to save time and reduce costs and are often stored for months before they are shipped from the manufacturer through distributors, shipping warehouses and other places. This can add up to 12 months or more from the time the product was made till it gets to your bathroom.  Parabens are very inexpensive and effective. This allows manufactures to make large quantities of a cosmetic product and store it for a long time which eases distribution problems and increases profits. Read more of this post