Protons are subatomic particles that are found in the nucleus of an atom. They have a positive charge, which balances out the negative charge of electrons and determines the overall charge of an atom. Protons are crucial in determining the identity of an element, as the number of protons in an atom's nucleus is what defines its atomic number. In addition to providing the positive charge in an atom, protons also play a role in holding the nucleus together. The strong nuclear force, which is mediated by particles called mesons, keeps protons and neutrons bound together in the nucleus. Protons are incredibly stable particles, with a half-life of at least 10^34 years. This stability is what allows atoms to exist in their current form and gives matter its structure. Without protons, the universe as we know it would not be possible.