A status-or-entry concept defining how a noncitizen is inspected, admitted, authorized to remain, or granted a lawful status category. It governs eligibility criteria, procedural steps, and documentation needed to obtain or maintain the relevant authorization. It does not authorize stay, work, or travel beyond the scope and validity of the granted status or document. It determines lawful presence, compliance obligations, and access to downstream benefits or relief mechanisms. The concept is generally stable, though eligibility criteria and documentation requirements are updated over time.