Joint sealants are materials used to fill gaps or joints between two surfaces to prevent the passage of fluids, dust, or other substances. They are commonly used in construction and engineering projects to provide a watertight and airtight seal between different building materials, such as concrete, metal, or wood. Joint sealants are also used to prevent the infiltration of water and other liquids into buildings or other structures, which can cause damage and deterioration over time. They come in a variety of forms, including liquid, paste, or pre-formed shapes, and are typically made of silicone, polyurethane, or other materials with similar properties.