Ordination of monks and nuns
During the Buddha’s time, the ordination gradually developed from a simple consent to join his Order to a more complex public ceremony.

The first few hundred students were personally ordained by the Buddha. They simply asked him for permission to join the order and he accepted and invited them in.

Later, as the Sangha grew, it was not possible for all the students to see the Buddha, so the Buddha instructed his best students to ordain some of them. The newcomers had to shave their heads and (in the case of men) beards and put on robes. Then they had to formally take refuge in the Buddha, Dharma and Sangha by reciting the Three Refuges.

Later, when some less suitable people wanted to join the Order, ten precepts were added to the Three Refuges.

Later still, after people complained of the behavior of some monks, more detailed rules of conduct were introduced for monks and nuns who completed their novice training. The total number of rules increased from ten to more than two hundred and twenty seven.

Monks and nuns in different traditions
Monks and nuns from different countries learn the Buddha’s Teaching in their own language. Their robes look different as they come from different traditions, either Theravada or Mahayana. Monks and nuns from the Theravada tradition come from Sri Lanka, Thailand, Myanmar, Cambodia, Laos. Those from Mahayana countries are Tibetan, Chinese, Vietnamese, Korean and Japanese.