A naturalization application is a formal request submitted by a foreign national to become a citizen of a country, typically after meeting specific residency and eligibility requirements. In the United States, this process involves filling out the N-400 form, providing documentation, and demonstrating knowledge of U.S. history and government. Once the application is submitted, the applicant will undergo a background check and an interview with a U.S. Citizenship and Immigration Services (USCIS) officer. If approved, the applicant will take an oath of allegiance, officially becoming a citizen and gaining the rights and responsibilities that come with citizenship.