A foreigner can be a citizen of another state by

A foreigner can become a citizen of another state through a legal process called "naturalization." This process involves an application to the country's government, meeting certain eligibility criteria, such as having a permanent residency status, passing a citizenship test, and renouncing the citizenship of the previous country of origin (in some cases). Once the requirements are met and the application is approved, the individual is granted citizenship of the country, with all the rights and responsibilities that come with it, such as the right to vote, hold public office, and access public services.