Paint thinners are solvents used to dilute or thin oil-based paints, varnishes, and other coatings. They help improve the flow and application of these products, making it easier to achieve a smooth finish. Common types of paint thinners include mineral spirits, turpentine, and acetone, each with specific properties and uses. In addition to thinning paint, paint thinners can also be used for cleaning brushes, tools, and surfaces that have been exposed to paint. However, they can be hazardous if inhaled or ingested, so it's important to use them in well-ventilated areas and follow safety guidelines.