Different categories of admission exist. No one can legally enter the United States without the official permission of this government.
Visas signify an official permission to enter.
Adult unmarried children of citizens, spouses and unmarried minor children of legal permanent residents, and married children of U.S. citizens may also be eligible for immigrant visas. Immediate relatives who want to request, or petition for their kin must also meet strict income requirements and be able to financially support the family member who will enter the United States on an immigrant visa. Executives, investors, highly skilled or professionally educated workers may also qualify for immigrant visas in employment-based categories. Employers based in the United States and employees agree together to apply for these visas. In many instances, the United States government expects many employers to demonstrate why foreign-born employees are essential for their firm, describe the tasks such employees will perform and the professional credentials or special experience such employees must have.