An escritura pública is the public deed drafted and authenticated by a notario público and recorded at the Public Registry of Property. It is the instrument that proves ownership of real estate in Mexico: until a purchase reaches a registered deed, you are not an owner — you are a party to a contract.
In practice
The distinction that costs foreign buyers the most money is this one: a private contrato de compraventa is a promise between two parties; the escritura is title, enforceable against everyone else. The private contract has its place — it reserves the lot and fixes the price and payment schedule — but it does not make you the owner and it does not protect you from a second sale of the same land.
In a Tulum land purchase the closing runs through the notaría: the notario reviews the chain of title and liens on the folio real, calculates and withholds the taxes, executes the deed and files it for registration. If you are a foreign buyer, the same deed creates the fideicomiso that the restricted zone requires. Closing costs in the Riviera Maya typically land between 6% and 8% of the price — acquisition tax, registry fees, notario fees — and they vary by municipality, so confirm the exact figure with your notario before you sign.
Watch out for
Any sale that stays in a private contract "to save on the notario," and any seller who cannot produce the folio real for what they are selling. A lot with no clear path to a deed — ejidal land without registered dominio pleno, for example — is not a bargain: it is property you will never be able to deed, sell, or pass on cleanly.
Related: Notario público · Fideicomiso · Dominio pleno · The full foreign-buyer guide