A popular food at SCA feasts. Tarts are easy to eat because you often don't need a plate or bowl to eat them off. They're simply a pastry base (often shortcrust pastry) with a filling in the middle. The difference between a pie and a tart is basically that a tart does not have a pastry lid.
You can fill tarts (and pies!) with whatever you feel like, and they're very easy to make. They can be sweet or savoury, and despite what many people in the SCA believe, you can make a tart without using either cloves or sultanas. You can make small tarts - known as tartlettes - or big tarts.
Note (from an English perspective: Tart has a secondary meaning, related to the lower end of the wenching sorority, and ladies of negotiable virtue. You can eat this sort of tart, but .... The difference between a wench and a tart is basically that a tart doesn't require persuading, just gold.