Naturalization is a term that refers to the entire process of becoming a US citizen. There are a number of different pathways that a person can take to qualify for naturalization. The first step is to get a green card, or become a permanent resident of the United States.
Although situations can vary, a person usually needs to be a green card holder for five years prior to qualifying for naturalization. There are different requirement to qualifying for naturalization if you are applying as the spouse or child of a US citizen. Members of the US Armed Forces are qualified for citizenship is many circumstances as well. Some of the other requirements of applying for naturalization include the ability to speak and read English, to have an understanding of how US civics works, and to be of good moral character. The naturalization process includes an interview and a test for sufficient knowledge of English and civics.
A Washington state immigration lawyer can provide more information regarding the naturalization process.