A "foreign corporation" in a state's corporate law refers to a corporation incorporated in another jurisdiction. The jurisdiction does not need to be outside the United States for the corporation to be a foreign corporation. In California corporate law, for example, a Delaware corporation would be a foreign corporation and a California corporation would be a domestic corporation. A foreign corporation is distinguished from a domestic corporation, which is one organized under that state's own law.
Foreign corporations are generally required to qualify in each state in which they transact business. The qualification process normally involves appointing an agent for service of process, paying a fee, and attesting to certain basic facts about the foreign corporation, although the requirements vary. The consequences of failing to qualify vary from state to state, but perhaps the most common consequence is the inability to access the court systems in those states.