Propolis or bee glue is a resinous mixture that honey bees produce by mixing
saliva and beeswax with exudate gathered from tree buds, sap flows, or other botanical sources. It is used as a sealant for unwanted open spaces in the hive.
Propolis is used for small gaps (approximately 6 millimeters (0.24 in) or less), while larger spaces are usually filled with beeswax. Its colour varies depending on its botanical source, with dark brown as the most common. Propolis is sticky at and above 20°C, while at lower temperatures it becomes hard and brittle.
While foraging, worker bees primarily harvest pollen and nectar, while also collecting water and tree resin necessary for the production of propolis. The chemical composition and nature of propolis depends on environmental conditions and harvested resources.
Due to its pharmacological properties, humans have shown increased interest in the use of propolis as an antibacterial, antifungal, antiviral, and antioxidant agent. People have used propolis for mummification, the treatment of disease, and as a burn treatment since ancient times.