Wikipedia
Shinbyu (; , also spelt shinpyu) is the Burmese term for a novitiation ceremony ( pabbajja) in the tradition of Theravada Buddhism, referring to the celebrations marking the sāmaṇera ordination of a boy under the age of 20.
It is deemed the most important duty that parents owe to their son by letting him go forth and embrace the legacy of the Buddha, join the Sangha and become immersed in the teachings of the Buddha, the Dhamma, at least for a short while, perhaps longer if not for the rest of his life. A boy may become a novice on more than one occasion, but by the age of twenty there will be another great occasion, the upasampada ordination, in which the boy becomes a fully ordained bazin . Those who are not blessed with a male child will seek for an orphan boy or a boy from very poor families in order to receive this special dispensation by the Buddha and hence gain great merit by the act. Shinbyu may well be regarded as a rite of passage or coming of age ceremony as in other religions. Allowing a son to spend some time however short it may be, in a Buddhist monastery is regarded by most Buddhists as the best religious gift that his parents can give him and it is believed to have a lasting effect on his life.