From a western perspective, Buddhism is accepted as a philosophy of the art of living whereas in oriental society, it is a religion with its own dogma, law, philosophy and tradition. In general, Buddhism is a teaching of Buddha Sakyamuni. So, the origin of Buddhism exists since the first sermon of Buddha in Saranath. But in depth, according to the inscription engraved in the stone pillars of Emperor Ashoka in 3rd century BC and some Buddhist literatures, many Buddhas existed before Sakyamuni Buddha. This proves that Buddhism belongs to ancient times, even before Sakyamuni, and he followed the path of ancient Buddhas.
The practice of Buddhism is to achieve a peace in mind by eliminating mental and physical suffering. The ultimate goal of this practice is attainting Nirvana (enlightenment). Buddha has talked about the four noble truths concerning the suffering and eight noble paths to eliminate this suffering. He has also taught the theory of cause and effect or depending origination or Karma and its result, impermanence, wisdom, compassion, five aggregates that help generating the suffering, sunyata or emptiness etc. The principal cause of suffering is ignorance that creates desire and aversion, then we grieve not acquiring what we desire and accepting what we dislike. Thus, eliminating the ignorance, we remove all the mental defilements that accomplishes sunyata, a stage of beatitude. The only way to realize Nirvana is practicing Pragya, Sila and Samadhi, where the true nature of elements of the universe can be observed that is sunyata or nothingness.
In Buddhism there are 3 principal holy books or Tripitaka (three baskets) – Suta Pitaka, Binaya Pitaka and Abhidhhama Pitaka. The first one is related to the teaching of Buddha. The second is the book on the code of conduct in the Buddhist community which documents solutions to problems arising in the Buddhist community at the time of Buddha. The third one is related to Buddhist philosophy. There is another book, Jataka, which is also important in Buddhism that details stories of Buddhas’ preceding lives. It is believed that once Buddha attained enlightenment, all his anterior lives appeared in his mind and explained himself to his disciples for moral education.
There are three different vehicles in Buddhism; Theravada, Mahayana or Paramitayana and Vajrayana. Historically these three developed bit by bit. But its believers do not agree with this theory and they say that Buddha taught Theravada in his first sermon in Saranath, he taught about Mahayana in Gridhkuta at Rajgiri 13 years after his enlightenment and 16 years after attaining Nirvana, he preached about Vajrayana in Dhanyakataka.
There is no doubt that Theravada is the most ancient among three. So, the ancient text of this vehicle is found in Pali language whereas literatures of other two are in Sanskrit language. It is believed that Buddha always taught in Pali language because of its profound used by the people while Sanskrit was common for aristocrat families and his aim was to cover all the people by his teaching. Theravada is a practice of Buddhism in which disciples train following the teaching of his master and attain the level of Arhata or state of beatitude where there is no more reincarnation. In Mahayana and Vajrayana, the concept of Bodhisattva, compassionate one, developed and altruism is practiced so practitioners can liberate themselves from suffering and help to accomplish Nirvana, which is the refusal of their own liberation until the enlightenment of all living being are realized. The notion of Sunyata is taught in Mahayana in which everything is soullessness. In Vajrayana, the goal is same but the method is different in the practice. It follows the path of esoterism amalgamate with meditation to release suffering of all being of the universe and aid to realize the enlightenment.
People from Sri Lanka, Myanmar, Thailand, Laos, Cambodia practice Theravada Buddhism while China, Japan, Korea, Vietnam are known for Mahayana Buddhism. Similarly, Nepal, Tibet, Bhutan, North of India, Mongolia adore Vajrayana Buddhism. In Tibet, the mountainous parts of Nepal and India along with Tibet and Bhutan practice Tibetan Buddhism or more broadly Himalayan Buddhism. In the capital of Nepal, people practice Vajrayana Buddhism and some Theravada Buddhism.