To render a binding judgment, a court must have both subject matter jurisdiction over the controversy (the subject of the dispute) and personal jurisdiction over the parties (plaintiff and defendant). While subject matter jurisdiction refers to the court’s power to hear a particular type of suit, personal jurisdiction—also known as in personam jurisdiction—concerns the court’s power to bind a particular person or party.

A special appearance is a procedure in civil litigation, and the purpose of a special appearance is to object to the court’s exercise of jurisdiction over the defendant or the defendant’s property on the ground that such person or property is not subject to the court’s jurisdiction. A defendant (person or entity) who has been sued in a state other than the defendant’s primary residence will often challenge the court’s exercise of jurisdiction over the nonresident defendant.

In Illinois, for a court to render a binding judgment, it must have both subject matter jurisdiction and personal jurisdiction. Subject matter jurisdiction is the court's authority to hear a specific type of case, which is determined by the nature of the issue at hand and statutory or constitutional provisions. Personal jurisdiction, on the other hand, refers to the court's power to make a decision affecting the rights of the specific parties involved. Illinois courts generally obtain personal jurisdiction over a party if that party has sufficient contacts with the state, such as residing in, doing business in, or committing a tortious act within the state. A special appearance is a tool used by a defendant to challenge the court's personal jurisdiction without submitting to it. In Illinois, this is governed by the Illinois Code of Civil Procedure. When a defendant makes a special appearance, they are arguing that the court does not have the legal authority to make decisions regarding them, typically because they do not have the requisite contacts with Illinois. It is important for a defendant to make a special appearance before taking any other action in the case to avoid inadvertently submitting to the court's jurisdiction.