Hiring foreign talent in the United States means operating two parallel systems at once: a temporary nonimmigrant system that authorizes someone to work for a specific employer for a defined period, and a permanent immigrant system that leads to a green card. This UpLaw guide maps both for startups and their counsel. It explains the H-1B specialty occupation standard and the numerical cap, lottery, and Labor Condition Application machinery that surround it; the O-1 extraordinary-ability classification that founders and senior researchers increasingly rely on; L-1 intracompany transfers, TN, E-1/E-2, and the F-1 OPT cap-gap; and then the employment-based green card categories EB-1 through EB-5, including PERM labor certification, the EB-2 National Interest Waiver under Matter of Dhanasar, priority dates and the Visa Bulletin, retrogression, and the choice between adjustment of status and consular processing. It closes with the compliance layer that quietly generates most of the liability in this field: the public access file, Form I-9, E-Verify, and government site visits. A running hypothetical, the fictional startup Halcyon AI, follows one engineer and one founder from first offer letter through permanent residence.