Look up "long arm statutes". State courts can have jurisdiction over out-of-state entities, subject to limitations established by federal precedent. Doing business with customers who reside in a state generally puts you under that state's jurisdiction, at least for purposes related to that business.

Comity iirc is the legal principle of mutually recognizing other states laws (giving them jurisdiction) as in recognizing a marriage contract in other states (and they recognize yours).

That's my guess