Puff pastry, also known as pâte feuilletée, is a light, flaky pastry, its base dough (détrempe) composed of wheat flour and water. Butter or other solid fat (beurrage) is then layered into the dough. The dough is repeatedly rolled and folded, rested, re-rolled and folded, encasing solid butter between each resulting layer.

This produces a laminated dough. During baking, gaps form between the layers left by the fat melting; the pastry is leavened by steam from the water content of the fat as it expands, puffing the separate layers. The pastry layers crisp as the heated fat is in contact with its surfaces.

While modern puff pastry was developed in France in the 17th century, related laminated and air-leavened pastry has a long history. In Spain, likely built upon Arab or Moorish culinary traditions, the first known recipe for pastry using butter or lard following the Arab technique of making each layer separately, appears in the Spanish recipe book Libro del arte de cozina ('book on the art of cooking') by Domingo Hernández de Maceras, published in 1607. Hernández, the head cook of a college of the University of Salamanca, already distinguished between filled puff pastry recipes and puff pastry tarts, and even mentions leavened preparations. Francisco Martínez Motiño, head chef to Philip II of Spain (1527–1598), also gave several recipes of puff pastry in his Arte de cocina, pastelería, bizcochería y conservería published in 1611. In this book, puff pastry is abundantly used, particularly to make savoury game pies.

The oldest known documented recipe for puff pastry in France was included in a charter by Robert, bishop of Amiens in 1311. The first recipe to explicitly use the technique of tourage (the action of encasing solid butter within dough layers, keeping the fat intact and separate, by folding several times) was published in 1651 by François Pierre La Varenne in Le cuisinier français. Modern French puff pastry was then developed and improved by the chef M. Feuillet and Antonin Carême.

The method is sometimes considered the idea of the famous painter Claude Gellée when he was an apprentice baker in 1612. Historical evidence for this is negligible, but it is retained as culinary lore. The story goes that Lorrain was making a type of very buttery bread for his sick father, and the process of rolling the butter into the bread dough created a croissant-like finished product.

The production of puff pastry dough can be time-consuming, because it must be kept at a temperature of approximately 16 °C (60 °F) to keep the shortening from melting and the layers melding; it must rest in between folds to allow gluten strands time to link up and thus retain layering. Therefore, between each step the dough is rested and chilled. Before re-rolling, the dough is rotated ninety degrees, so that it is rolled at right angle relative to the previous "turn" (as each step is usually referred to). After rolling, another thin layer of butter is applied, the folding and resting are repeated. The chef Julia Child's method has 72 layers for rough-puff pastry (pâte demi-feuilletée) and 729 layers for pâte feuilletée fine.

The number of layers in puff pastry is calculated with the formula:

where ${\displaystyle \ell }$ is the number of finished layers, ${\displaystyle f}$ the number of folds in a single folding move, and ${\displaystyle n}$ is how many times the folding move is repeated. For example, twice-folding (i.e. in three), repeated four times gives ${\displaystyle (2+1)^{4}=81}$ layers.