A foreign citizen that intends to travel to the USA must get a visa to do so. Both the nonimmigrant visa meant for temporary stay and the immigrant visa for permanent residence requires the applicant to get a visa first. Citizens of certain qualified countries can go to the U.S. without a visa and this is applicable under the Visa Waiver Program. All individuals that intend to come to the United States under the Visa Waiver Program must be authorized through the Electronic System for Travel Authorization (ESTA) system before starting the process of travelling to the United States.
Individuals from other countries that do not qualify for the Visa Waiver Program or are traveling to study, work, taking part in an exchange program, or any other reason that does not fall under a B visa, will need a nonimmigrant visa.
Obtaining a visa however does not guarantee entry to the United States. The visa is to imply prove that a U.S. consular officer has decided that you are eligible to apply for entry to the United States for a certain reason.
The nonimmigrant visa is applied or by tourists, business people, students, or specialty workers who intend to stay for a certain period of time in the United States for certain reasons. According to U.S. visa laws and regulations, most nonimmigrant visa applicants must prove to the consular officer that they have strong ties to their country of residence and must prove that they intend to depart the United States after their temporary authorized stay. In Nigeria, you can apply for a nonimmigrant visa at the U.S. Embassy in Abuja and the U.S. Consulate General in Lagos.
Immigrant visas are for individuals who intend to live permanently in the United States. The immigrant visa allows for application for admission to the United States as a Legal Permanent Resident and is a step toward obtaining the U.S. citizenship. Most immigrant visa applications starts when a qualified family member who is a U.S. citizen or legal permanent resident submits a petition on behalf of the immigrant to the U. S. Citizenship & Immigration Services (USCIS) in the United States. It is also possible for an employer in the U.S. to file a petition for a foreign national whom the employer intends to hire for an eligible position permanently. The U.S. Embassy in Abuja does not process immigrant visa applicants. Applicants from all over Nigeria apply for the immigrant visa at the U.S. Consulate General in Lagos.