N. Very simply, a tart is a pastry crust with shallow sides, a filling and no top crust. The filling can be sweet (such as fruit or sweet custard) or savory (like meat, cheese or savory custard). Depending on the type of tart, the pastry shell can be baked and then filled, or filled and then baked. Tarts can be bite-sized (often served as hors D'oeuvre), individual-sized (sometimes called tartlets) or full-sized. They can be used as appetizers, entrées or desserts. See also tarte tatin. tart adj. Sharp, acidic or sour.