What is the difference between an 'urfi (customary) marriage and a shar'i (Islamic legal) marriage, is the difference between them in public knowledge versus secrecy, and are both permissible or forbidden?

An 'urfi' marriage can be legitimate if it fulfills the conditions and pillars of a valid marriage, even if it is not officially documented. It can be null and void if it is performed without a guardian (wali) or witnesses. If the conditions for validity are met, it is not considered a secret marriage by the majority of jurists, and its declaration is recommended. However, the Malikis consider it a secret marriage if the husband instructs the witnesses to conceal it.