Theravada (from the Pali Thera, meaning stability or motionlessness) is the original and fundamental Buddhist religious philosophy. A person who becomes a Bhiksu (monk) after renouncing his family and who practises complete abstinence from worldly pleasures for at least 10 years becomes a thera. Theravada is derived from the practice of thera by Bhiksus. It is said that this practice was introduced at the first assembly of Buddhist Bhiksus after the death of gautam buddha. Theravada is practiced by Buddhists in Bangladesh and many other Asian countries.

Buddhism was founded in the 6th century BC by Gautam Buddha. Later, messages and teachings of the Buddha were compiled into the tripitaka, the Buddhist scriptures, written in pali. The Tripitaka contains not only the philosophy of Buddhism but also guidelines considered essential to regulate every aspect of a Bhiksus's life. The original philosophy and religious practices as contained in the Pali Tripitaka are known as Theravada.

The evolution of Buddhism can be divided into three phases. The first phase, which lasted about 550 years, extended from the 6th century BC up to the beginning of the Christian era. The second phase extended from the 1st century AD to the 7th century and the third phase from the 8th century to the 12th century. The Buddhism of the first phase was Theravada. The second phase saw the appearance of the mahayana philosophy. During this time the Tripitaka was translated into Sanskrit and other Indian languages in abridged form. This led to the discarding of the severity of many traditional practices. The followers of these relaxed practices or Mahayanas termed Theravada conservative Buddhism, hinayana or Sthaviravada. There is no fundamental difference in the philosophies of the different sects. However, they differ in the observance of some practices.

The followers of Theravada or Hinayana observe strictly the ways shown by the Buddha in removing from one's mind ignorance, desire and lust, aimed at attaining nirvana. On the other hand, the followers of Mahayana observe the ideals of the Buddha.

It is known that Mahayana was practiced in some areas of Bangladesh in the 7th and 8th centuries. At present, Buddhists in Bangladesh follow Theravada. [Suman Kanti Barua]