A lemon tart is a dessert dish, a variety of tart. It has a pastry shell with a lemon flavored filling.
In the UK, lemon tart consists of a pastry case (often made in a fluted tart tin) containing a baked lemon custard (usually composed of eggs, sugar, lemon juice and cream). Usually recipes include blind-baking before adding the custard. Sometimes the tart is dusted with icing sugar prior to serving.
Alternatively, the lemon filling can be cooked in a saucepan and then added to the baked pastry case.
A dessert very similar to the lemon tart is the lemon pie, usually served for dessert, made with a crust usually made of shortcrust pastry and lemon custard filling. The lemon pie is prepared with a bottom pie crust. This pie is different from the lemon meringue pie, which has meringue on top. No upper crust is used, as in a cherry pie.