Swami Vivekananda (1863-1902 C.E.) was a Hindu monk and a patriotic saint of India. According to English calendar he was born on 12th January 1863 into an aristocratic Bengali family of Calcutta. According to Hindu calendar Vivekananda was born on Krishna Paksha Saptami after seven days of Paush Purnima. His birthday is also celebrated according to Hindu calendar and this day is known as Swami Vivekananda Jayanti. As Jayanti day is decided based on Hindu calendar, it is not fixed on Gregorian calendar like Rabindranath Tagore Jayanti and Mahatma Gandhi Jayanti which are celebrated on fixed day on Gregorian calendar.
However Indian government has decided to observe Swami Vivekananda's Gregorian date of birth as National Youth Day. Hence National Youth Day of India is celebrated each year on 12th January since 1985.
Swami Vivekananda was modern Hindu saint and follower of Vedanta philosophy of Hinduism. He was disciple of Ramakrishna. He founded Belur Math, Ramakrishna Math and Ramakrishna Mission.