The primary fuel used in lighters is butane. This hydrocarbon is a colorless, odorless gas that is highly flammable, making it an ideal fuel for portable lighters. Butane lighters are widely used due to their convenience and reliability. According to the National Fire Protection Association (NFPA), butane is the most common fuel used in lighters, accounting for approximately 80% of the market share in the United States. The popularity of butane is attributed to its ease of ignition, long burn time, and low cost. Additionally, butane lighters are designed to be safe for use in various environments, including indoors, as they emit minimal amounts of carbon monoxide and other harmful gases. The widespread use of butane in lighters is further supported by data from the U.S. Consumer Product Safety Commission, which reports that butane lighters are responsible for a significant number of accidental fires and burns each year, emphasizing the importance of proper usage and storage.