What is the difference between an immediate relative and a family preference category?

U.S. family-based immigration is divided into two main tracks. Immediate relatives of U.S. citizens include spouses, unmarried children under 21, and parents of U.S. citizens who are at least 21. Visas for immediate relatives are unlimited, so they are always available and these cases generally move faster.

Family preference categories cover more distant relationships of U.S. citizens and certain relationships of lawful permanent residents. These categories are subject to annual numerical limits set by Congress, which means beneficiaries can immigrate only when a visa becomes available based on their priority date. This distinction is one of the most important factors in how long a case takes.