Baryon number conservation is a fundamental principle in particle physics stating that the total baryon number in a closed system remains constant over time. Baryons, such as protons and neutrons, have a baryon number of +1, while antibaryons have a baryon number of -1. Other particles, like leptons, have a baryon number of 0. In any physical process, including nuclear reactions and particle collisions, the sum of baryon numbers before and after the event must be equal. This conservation law helps scientists understand interactions in high-energy physics, including those studied in particle accelerators like the Large Hadron Collider.