Dryer sheets help prevent static electricity caused by fabrics tumbling in a dryer. This static charge is built up where clothes rub together. The rubbing can knock loose electrons from some fabrics onto others. So while some fabrics may have many electrons, others could have more protons, causing them to attract to one another. Dryer sheets are naturally positively charged and provide a lubricating effect after they coat the clothing. By lubricating the clothing, friction is significantly reduced, which reduces the bonding/separating frequency that is causing the static charge to build up. Thus, dryer sheets are typically impregnated with a heat activated, waxy substance which works as a fabric softener and coats the clothing with a very thin layer of lubrication, reducing friction and static charge buildup.