IN MOST countries, citizenship is obtained through either birth, marriage, or a procedure called naturalisation.

To be naturalised, one needs to have lived in the country for a certain amount of time as a permanent resident.

Some countries, like the United States, Canada, Britain and Australia, require prospective citizens to take a test.

Those in Britain have to take a computer-based test of 24 questions in 45 minutes.

Questions are based on material in an official handbook covering British history, society, politics, law, everyday needs like housing, health, education, money, leisure, employment, and where to go for help.

In the US, a permanent resident or "green card holder" of at least five years can apply to take the naturalisation test, which consists of an interview and an English language and civics test.

Other countries have particular requirements.

To become a Swiss citizen, one needs to have resided in Switzerland for at least 12 years.

Time spent there between the ages of 10 and 20 counts double.

A Swiss citizen is a citizen at three levels: his community, his state and the Confederation.

The community that a new citizen lives in may impose other requirements, such as fluency in either German, French, Italian or Romansh.

Thailand sets an immigration quota of 100 persons a year from each country.

Aside from residency, tax and other requirements, applicants must be able to speak and understand the Thai language, sing the National Anthem and pass an interview in Thai with officials.

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This article was first published in The Straits Times.