The Registro Público de la Propiedad y del Comercio (RPPC) is the state-level public registry where title, ownership and liens on real estate are recorded in Mexico. Every registered property has a folio real — its unique file, holding the chain of owners and any encumbrance attached to it.
In practice
This is where you, or your notario acting for you, confirm who actually owns a lot and whether it carries mortgages, judgments, litigation or easements. It is the single most important check in the whole purchase, and it happens before any money moves: a folio real in the seller's name, plus a recent lien-free certificate (certificado de libertad de gravamen).
Ask for both documents freshly dated; a certificate pulled months ago says nothing about today. If a parcel does not appear in the registry, it is not yet titleable private property. That is the signature of ejido or irregular land, and where the history is agrarian the check finishes at the Registro Agrario Nacional (RAN) rather than the RPPC.
After closing, your deed goes back to the RPPC to be recorded in your name. That recording, not the private contract, is what makes you owner against the rest of the world.
Watch out for
Private "cesión de derechos" contracts that never reach a notario or the registry. Without recording there is no practical defense against a double sale: whoever records first prevails, and the second buyer is left with paper and a lawsuit. Pay only against notarized, recordable instruments.
Related: Escritura · Ejido · Fideicomiso · How to verify a Tulum development is legal