Protons and electrons possess an equal magnitude of electric charge. This fundamental property of subatomic particles is a cornerstone of atomic structure and the electrical neutrality observed in macroscopic matter. While the quantity of charge is identical, their signs are opposite: the proton carries a positive charge, while the electron carries a negative charge.
The balance of these charges is essential for the stability of atoms and molecules. Were this balance not present, matter would exhibit significant and potentially destabilizing electrical forces. Furthermore, the precise quantification of these fundamental charges has allowed for the development of numerous technologies and a deeper understanding of electromagnetic phenomena. Historically, determining the exact relationship between proton and electron charge was crucial in solidifying the atomic model and developing quantum mechanics.