The proton was discovered by Ernest Rutherford in 1917. He identified the proton as the hydrogen nucleus during experiments where he bombarded nitrogen gas with alpha particles and observed the emission of positively charged particles. These particles were later recognized as protons, which are present in the nuclei of all atoms except hydrogen itself, where the nucleus is just a single proton. Although Eugen Goldstein is credited with observing positive particles (canal rays) earlier, the discovery and naming of the proton as a fundamental subatomic particle are attributed to Rutherford.