Sealants are commonly used in construction and are important for keeping air and water from entering gaps or spaces in buildings. There are numerous synonymous words for sealants, including caulks, fillers, putties, mastics, adhesives, and sealers. These words all describe materials that are used to fill gaps, seal areas, or bond surfaces together. Caulks are usually made from a flexible material, such as silicone or rubber, and are used to seal around doors and windows, while fillers like plaster or spackle are used to smooth over surfaces. Putties can be used to fill large gaps, while mastics and adhesives are used to bond surfaces together. Sealers are protective coatings applied over surfaces to keep water or other materials from penetrating.