Tubeless sealant is a liquid solution used in tubeless tyre setups to seal punctures and small leaks in the tyre's casing. It's typically made of latex or synthetic compounds mixed with particles like microfibers or crystals. When a puncture occurs, the sealant flows into the hole, quickly sealing it to prevent air from escaping. This helps maintain tyre pressure and reduces the need for immediate repairs, enhancing the reliability and performance of tubeless tyre systems.