Personal jurisdiction is the authority a court has to make legally enforceable orders related to a person or entity and the property of the person or entity, and usually arises when a person has been sued in a lawsuit. For a court to have personal jurisdiction, the person or entity generally (1) must be a resident of the state in which the court is located; (2) as a nonresident, must have initiated sufficient minimum contacts with the state in which the lawsuit is filed; or (3) must have agreed to be governed by the laws of the state (in a contract or website terms) in which the lawsuit is filed.

In Illinois, personal jurisdiction refers to the power of a state court to bring a person or entity into its court system and to make decisions that are legally binding upon them. For an Illinois court to establish personal jurisdiction, the defendant must typically have a substantial connection to the state. This can be established if the defendant is a resident of Illinois or if the defendant, as a nonresident, has engaged in activities that constitute sufficient minimum contacts with Illinois. Such contacts can include conducting business, owning property, or committing a tortious act within the state. Additionally, a nonresident may consent to Illinois's jurisdiction by agreeing to it in a contract, such as through a forum selection clause, or by using a website with terms that specify Illinois law will govern disputes. Illinois courts also follow federal due process standards, which require that exercising jurisdiction must not violate traditional notions of fair play and substantial justice.