Good question. In much of the English-speaking world, the term “galette” is associated with a sort of free-form pie or tart. This isn’t so in France, where a galette is a thick, savory buckwheat crêpe. How the word ever came to describe a free-form fruit tart is a mystery (at least to me). It’s not as though the French don’t make these sorts of rustic tarts. They do — and in great quantity. They just call them “tarts”. ‘Nuff said.
New World galettes start with a round of pastry dough. A quantity of filling (usually fruit, but it can be things like potato or roasted vegetable) is placed in the center and the edges are folded up to partially enclosed it. That’s pretty much it. The pastry is most often pie or tart dough, but can also be puff or flaky pastry for those who wish to get fancy.