A muffin is a type of individual-sized baked good. It is often a small, sweet quickbread or cake in a cup-shaped container. It may be named for additional ingredients, e.g., "blueberry muffin".

While quickbread "American" muffins are often sweetened, there are savory varieties made with ingredients such as cornbread muffins and cheese muffins, and less sweet varieties such as traditional bran muffins. The quickbread muffin originated in North America during the 19th century.

One 19th-century source suggests that muffin may be related to the Greek bread maphula, a 'cake baked on a hearth or griddle', or from Old French mou-pain 'soft bread', which may have been altered into mouffin. The word is first found in print in 1703, spelled moofin; it is of uncertain origin but possibly derived from the Low German Muffen, the plural of Muffe, meaning 'small cake', or possibly with some connection to the Old French moufflet meaning 'soft', as said of bread. The expression muffin-man, meaning a street seller of muffins, is attested in a 1754 poem, which includes the line: "Hark! the shrill Muffin-Man his Carol plies."

Quickbread muffins (sometimes described in Britain as "American muffins") are baked, individual-sized, cupcake-shaped foods with a "moist, coarse-grained" texture. Muffins are available in both savoury varieties, such as cornmeal and cheese muffins, or sweet varieties such as blueberry, chocolate chip, lemon or banana flavours. Sweetened muffins range from lightly sweetened muffins to products that are "richer than many cakes in fat and sugar." They are similar to cupcakes in size and cooking methods, the main difference being that cupcakes tend to be sweet desserts using cake batter, often topped with sugar icing (American frosting). Muffins may have solid items mixed into the batter, such as berries, chocolate chips or nuts. Fresh baked muffins are sold by bakeries, donut shops and some fast food restaurants and coffeehouses. Factory-baked muffins are sold at grocery stores and convenience stores, and are served in some coffee shops and cafeterias.

Recipes for quickbread muffins are common in 19th-century American cookbooks. Recipes for yeast-based muffins, which were sometimes called "common muffins" or "wheat muffins" in 19th-century American cookbooks, can be found in much older cookbooks. In Fannie Farmer's Boston Cooking-School Cook Book, she gave recipes for both quick bread muffins and English muffins.

Over the years, the size and calorie content of muffins has changed: the 3-inch muffins grandmother made had only 120 to 160 calories. But today's giant bakery muffins contain from 340 to 630 calories each.

Quickbread muffins are made with flour, sieved together with bicarbonate of soda as a raising agent. To this is added butter or shortening, eggs and any flavourings (fruit, such as blueberries, chocolate or banana; or savouries, such as cheese).

Commercial muffins may have "modified starches", corn syrup (or high-fructose corn syrup), xanthan gum, or guar gum to increase moisture content and lengthen shelf life (these gums can also make added solids, such as chocolate chips, disperse more evenly in the batter).