The categories of "tart", "flan", and "pie" overlap, with no sharp distinctions.

Tarts are thought to have either come from a tradition of layering food or to be a product of medieval pie making.

Enriched dough (i.e. shortcrust) is thought to have been first commonly used in 1550, approximately 200 years after pies.

[2] Early medieval tarts generally had meat fillings, but later ones were often based on fruit and custard.

[4] Tarts are typically free-standing with firm pastry base consisting of dough, itself made of flour, thick filling, and perpendicular sides while pies may have softer pastry, looser filling, and sloped sides, necessitating service from the pie plate.