The primary substance used to create glass is silica, which is derived from sand. Silica crystals are combined with other materials, such as soda ash and limestone, and then heated to extremely high temperatures until they melt. This process forms a liquid that can be molded into various shapes, which upon cooling solidifies into glass. Different additives can modify the properties of glass, such as its color and transparency, leading to various types of glass used in windows, containers, and artistic creations. Glassmaking is an ancient craft that continues to evolve today.