The country is multi-ethnic and multi-cultural, which has a significant effect on its politics. About half the population is ethnically Malay, with minorities of Chinese, Indians, and indigenous peoples. The country's official language is Malaysian, a standard form of the Malay language. English remains an active second language. While recognising Islam as the country's established religion, the constitution grants freedom of religion to non-Muslims. The government is modelled on the Westminster parliamentary system and the legal system is based on common law. The head of state is an elected monarch, chosen from among the nine state sultans every five years. The head of government is the Prime Minister.