The elementary particle with the smallest known mass is the neutrino. Neutrinos are incredibly light, electrically neutral particles that are produced in vast quantities by nuclear reactions, such as those occurring in the sun and during supernova explosions.
Although mass measurements have improved, neutrinos are generally understood to possess a mass extremely close to zero, making them difficult to detect. Their mass is so small that it is often considered negligible compared to other elementary particles like electrons, protons, and neutrons.
The unique properties of neutrinos, including their tiny mass and weak interaction with matter, make them fascinating subjects of study in both particle physics and cosmology. Ongoing experiments continue to refine our understanding of neutrino masses, and they challenge our current models of particle physics.