There are two ways to become a citizen of the United States. First, you can become a citizen by being born in the US, or have parents who are US citizens. Because this kind of citizenship is automatic, you may be a US citizen and not even know it. The second path to citizenship is to apply for naturalization. If you succeed, you will be granted US citizenship once you take the citizenship oath.
We also list the process and requirements for naturalization. This overview doesn't cover all of the possibilities. For example, the rules and requirements sometimes change, depending on the exact date that you or your parents were born. There are also some unique rules for people born in certain places like American Samoa and the Panama Canal Zone, and for people who were adopted by US citizens.