Answer
An action to quiet title, governed by Civil Code Articles 476 to 481, has two indispensable requisites. First, the plaintiff must have a legal or equitable title to, or interest in, the real property that is the subject of the action. Second, there must be a cloud on that title — an instrument, record, claim, encumbrance, or proceeding that appears valid or effective but is in truth invalid, ineffective, voidable, or unenforceable, and that is prejudicial to the plaintiff's title (Article 476).
The purpose is to remove the cloud and secure the plaintiff's title, so that the owner and those claiming under him may be free from any hostile claim. The action also lies to remove a cloud arising from an instrument or obligation that has already been extinguished or barred by prescription but still appears of record (Article 478).