Paraffin is a waxy substance made from petroleum (the same crude oil used to make gasoline). It's white or colorless, feels slippery and slightly greasy, and melts easily when heated.

You encounter paraffin more often than you might realize. Most candles are made from paraffin wax: when you light a birthday candle, the flame melts the paraffin, which then burns to produce light. Paraffin also appears in crayons, giving them their smooth, colorful coating. Wax paper used for wrapping sandwiches gets its water-resistant properties from a thin paraffin coating.

Before electric refrigerators existed, people used paraffin to seal homemade jams and jellies in jars, creating an airtight barrier that kept food fresh. Some people still use this method today when canning. Paraffin is also used in ski wax to help skis glide smoothly over snow, and it appears in some cosmetics and medicines.

Paraffin's stability makes it perfect for candles: it burns slowly and steadily rather than flaring up dangerously. While paraffin comes from fossil fuels, scientists have developed alternative waxes from soybeans and beeswax for people who prefer natural materials.