Article IV sets up terms of cooperation and respect amongst states. Citizens of one state must enjoy the rights of the citizens of any state. Any fugitive from justice from one state shall be returned to it by the state to which he flees, documents, laws, and judicial decisions of one state shall be respected by other states.
The article also allows that Congress may admit new states and regulate U.S. territories and property. It guarantees a republican form of government to the states, and it requires that the federal government protect the states from invasion and, upon request, internal violence.
