Glass is made by heating sand, soda ash, and limestone in a furnace. This produces a molten material that can be shaped and cooled. Glass has been used for thousands of years and is now one of the most versatile engineering materials. Its composition and properties can be varied for different applications through the addition of different materials during production. Common types include soda-lime glass for windows and bottles and lead crystal for its brilliance. The document discusses the ingredients, production process, types, and uses of glass.