Delaware law requires every corporation or LLC to have and maintain both a “registered office” and a “registered agent” in Delaware. A registered agent is a responsible third-party who is registered in the same state in which a business entity was established and who is designated to receive service of process notices, correspondence from the Secretary of State, and other official government notifications, usually tax forms and notice of lawsuits, on behalf of the corporation or LLC. The theory of the law requiring all Delaware entities to have a registered agent and a registered office in Delaware is that there must be an actual person residing at an actual physical address in Delaware to receive important papers so that the Delaware courts will have jurisdiction over the entity.
A registered office is simply the physical location within a state where the registered agent can be located or contacted.