A tart is a baked dish consisting of a filling over a pastry base with an open top not covered with pastry. The pastry is usually shortcrust pastry; the filling may be sweet or savoury, though modern tarts are usually fruit-based, sometimes with custard. Tartlet refers to a miniature tart; an example would be egg tarts. Examples of tarts include jam tarts, which may be different colours depending on the flavour of the jam used to fill them, and the Bakewell tart.The categories of 'tart', 'flan', 'quiche' and 'pie' overlap, with no sharp distinctions, though 'pie' is the more common term in the United States. The French word tarte can be translated to mean either pie or tart, as both are mainly the same with the exception of a pie usually covering the filling in pastry, while flans and tarts leave it open. The Italian crostata, dating to at least the mid-1400s, has been described as a "rustic free-form version of an open fruit tart".Early medieval tarts generally had meat fillings, but later ones were often based on fruit and custard.Tarte Tatin is an upside-down tart, of apples, other fruit, or onions.Savoury tarts include quiche, a family of savoury tarts with a mostly custard filling; German Zwiebelkuchen 'onion tart', and Swiss cheese tart made from Gruyere.