Vajrayana is one of the major schools of Buddhism which originated in Gandhara (modern-day Pakistan). It is sometimes called esoteric Buddhism. Padmasambhava from Gandhara brought Buddhism to Tibet. It later spread to Mongolia and Bhutan. Since the annexation of Tibet by the People's Republic of China in 1959, the Tibetan form of Vajrayana has spread to many Western countries and has gained great popularity.
Vajrayana is a third and separate major school of Buddhism, the other two being Theravada and Mahayana. Vajrayana Buddhism comes from Mahayana Buddhism. Tibetan Vajrayana Buddhism has its own texts in the Tibetan and Sanskrit languages. It also contains the older Mahayana texts in Sanskrit and Theravada texts in the Pali language.
Vajrayana is sometimes known as Tantric Buddhism in the west. Tantric practice is one kind of Vajrayana Buddhism, but there are also other forms.
Vajrayana Buddhism is also known as "The Diamond Vehicle".