The main substance found in glass is silica (silicon dioxide, SiO2). Silica is a natural compound that is the primary component of the sand used in glass manufacturing. When heated to high temperatures, silica melts and forms a viscous liquid that can be molded and shaped into various types of glass. Additional materials, such as soda ash and lime, are often added to lower the melting point and improve the durability of the finished product. The resultant glass can then be processed for numerous applications, including windows, containers, and decorative items.