Glue is a substance used to attach two or more materials together. Glue can be made in various ways and consists of a mixture of different substances, depending on the type of glue and the purpose for which it is used. Some glues are water-based and can be easily dissolved with water, while other glues are solvent-based and require the use of solvents to remove. Glue can be used to bond a variety of materials together, such as wood, metal, plastic, synthetic, paper, and leather. It is often used in industry, at home, and in crafts.