Emphyteusis is the legal term for what’s commonly called ground rent or ċens in Malta - a contract granting a tenement in perpetuity or for a fixed term against a yearly rent. Where the grant is perpetual, the holder (the emphyteuta) has the right to redeem it, becoming full owner by paying 20 times the annual ground rent.
See the full Ground Rent guide for what to check before buying a property subject to ground rent, and how redemption works in practice.