Nationality law (or citizenship law) is the law in each country and in each jurisdiction within each country which defines the rights and obligations of citizenship within the jurisdiction and the manner in which citizenship is acquired as well as how citizenship may be lost. A person who is not a citizen of the country is generally regarded as a foreigner, also referred to as an alien. A person who has no recognised nationality or citizenship is regarded as stateless.
Nationality law can be broadly categorised into three principles, jus soli, or right by birth on the soil, jus sanguinis or right of the blood, jus matriomii, or right of marriage. Laws may be based on any of these principles, but commonly is a combination of all three principles. Generally speaking, new world countries have a strong jus soli heritage (along with common law countries, until very recently, with the exception of the United States and Canada)