A petit four (plural: petits fours) is a small confection generally eaten at the end of a meal (e.g., with coffee) or served as part of dessert. The name is from the French petit four, meaning "small oven".
There are two different categories of petits fours. Petits fours secs (sec meaning "dry") include a variety of small desserts, such as special dainty biscuits, baked meringues, macarons, and puff pastries. Petits fours glacés (glacé meaning "iced") are iced or decorated in some way, such as tiny cakes covered in fondant or glacé icing, small éclairs, and tartlets. In a French patisserie, assorted small desserts are usually called mignardises, while hard, buttery biscuits are called petit fours.
There are also petits fours salés (salé meaning "salted" or "savoury"), which are bite-sized salted appetizers usually served as part of cocktail parties or buffets.
Petits fours were traditionally made during the cooling process of coal powered, brick ovens in the 18th century. This was due to coal's high burning temperature, relative to wood, and its expense at the time. Wasting the heat produced was not an option.