Jurisdiction determines a court's authority to hear and decide cases; absence cannot be cured by consent. Jurisdiction denotes a court's authority to entertain, hear and decide matters, with limits imposed by the statute, charter or commission constituting the forum and by reference to the kind of claims or territorial area; where no restriction exists jurisdiction is unlimited. Jurisdiction is essential, cannot be waived or conferred by consent, and courts may determine their own jurisdiction; absence of jurisdiction renders proceedings and orders a nullity.