The U.S. Citizenship and Immigration Services (USCIS) is a government agency that oversees lawful immigration to the United States. It is responsible for processing applications for various immigration benefits, including green cards, citizenship, and work permits. USCIS aims to ensure that the immigration process is fair and efficient. USCIS also provides resources and information to help immigrants understand their rights and responsibilities. The agency conducts interviews, reviews applications, and makes decisions on immigration cases. Additionally, USCIS plays a role in promoting national security and preventing fraud in the immigration system.