Thinners are solvents used to reduce the viscosity of paints, varnishes, and other coatings, making them easier to apply. Commonly made from chemicals like toluene, acetone, or mineral spirits, thinners help achieve a smoother finish and improve drying times. They are essential in various applications, including art, construction, and automotive refinishing. In addition to their use in painting, thinners can also clean brushes and tools, removing dried paint and residue. However, it's important to handle thinners with care, as they can be flammable and may release harmful fumes. Proper ventilation and protective gear are recommended when using these substances.