An apple pie is a fruit pie (or tart) in which the principal filling ingredient is apples. It is sometimes served with whipped cream or ice cream on top. Pastry is generally used top-and-bottom, making it a double-crust pie, the upper crust of which may be a disk shaped crust or a pastry lattice woven of strips; exceptions are deep-dish apple pie with a top crust only, and open-face Tarte Tatin.

Cooking apples (culinary apples, colloquially cookers), such as the Bramley or Granny Smith, are crisp and acidic. The fruit for the pie can be fresh, canned, or reconstituted from dried apples. This affects the final texture, and the length of cooking time required; whether it has an effect on the flavour of the pie is a matter of opinion. Dried or preserved apples were originally substituted only at times when fresh fruit was unavailable.

In the English colonies the apple pie had to wait for carefully planted pips, brought in barrels across the Atlantic, to become fruit-bearing apple trees, to be selected for their cooking qualities. In the meantime, the colonists were more likely to make their pies, or "pasties", of meat rather than of fruit; and the main use for apples, once they were available, was in cider. But there are American apple-pie recipes, both manuscript and printed, from the eighteenth century, and it has since become a very popular dessert.

A mock apple pie made from crackers was apparently invented by pioneers on the move during the nineteenth century who were bereft of apples. In the 1930s, and for many years afterwards, Ritz Crackers promoted a recipe for mock apple pie using its product, along with sugar and various spices.

Although apple pies have been eaten since long before the European colonization of the Americas, "as American as apple pie" is a saying in the United States, meaning "typically American". The dish was also commemorated in the phrase "for Mom and apple pie" - supposedly the stock answer of American soldiers in World War II, whenever journalists asked why they were going to war.

Advertisers exploited the patriotic connection in the 1970s with the commercial jingle "baseball, hot dogs, apple pie and Chevrolet". There are claims that the Apple Marketing Board of New York State used such slogans as "An apple a day keeps the doctor away" and "as American as apple pie!", and thus "was able to successfully 'rehabilitate' the apple as a popular comestible" in the early twentieth century when prohibition outlawed the production of cider.

The unincorporated community of Pie Town, New Mexico is named in honor of the apple pie.