Pâte brisée ‘broken pastry’, gets its name from the fact that the flour and very cold fat (butter and/or lard) are cut into each other before adding water. This creates pockets of air that form when baking. The trick is to not overwork it. If you finally give up you can buy it readymade (the cheap ones aren’t always that great.)
Variations on pâte brisée include
pâte à foncer: with the addition of an egg yolk and some sugar, to make a firmer crust
pâte sucrée: similar to sablée, but with less butter, whole eggs and powdered sugar. It’s often used for a flan pâtissier.
Image by Romain Behar