Swami Vivekananda, born Narendranath Datta in 1863, was a significant reformer who shaped modern India through his advocacy for universal religion and religious tolerance. He gained international recognition after his impactful speech at the Parliament of the World's Religions in 1893, promoting the unity of all religions and the ideals of 'renunciation and service.' Vivekananda founded the Ramakrishna Math and the Ramakrishna Mission, focusing on spiritual and humanitarian efforts in education, healthcare, and social welfare.