If you are a lawful permanent resident of five years or married to a U.S. citizen and have a continuous residence in the U.S., you can apply for naturalization. Naturalization is when a noncitizen born outside of the U.S. becomes a U.S. citizen of their volition. However, certain eligibility criteria must be met.
For example, if you are married to a U.S. citizen, you will be able to apply for naturalization three years after getting married and becoming a lawful permanent resident. If you become a lawful permanent resident through one of the immigrant visas programs, such as talent visa, work visa, investor visa, and so on, you can apply for naturalization five years after obtaining your status.
You must file your application with the USCIS by submitting form N-400 along with corroborating documents. Once your document packet has been received and processed, you will be scheduled for an interview with an immigration officer and undergo a citizenship exam. The exam is conducted in English (exclusions apply) and consists of questions about the principles and form of government, politics and history of the U.S. Upon successfully passing the exam you will receive a "Certificate of Naturalization" and, subsequently, a U.S. passport.
Although you already have a permanent resident status, and obtaining citizenship may seem like the next easy step, there are many pitfalls. The interview process is quite stressful, challenging and confusing. It is important not only to pass the exam and answer all questions correctly, but also to demonstrate that you have been a person of good moral character, attached to the principles and ideas of the U.S. Constitution and are ready to take an Oath of Allegiance to the U.S.
You will only have two attempts to pass the exam. Failure to do so will result in denial of a naturalization.