Apples appear in many religious traditions, often as a mystical or forbidden fruit. One of the problems identifying apples in religion, mythology and folktales is that as late as the 17th century, the word "apple" was used as a generic term for all (foreign) fruit other than berries, but including nuts. This term may even have extended to plant galls, as they were thought to be of plant origin (see oak apple). For instance, when tomatoes were introduced into Europe, they were called "love apples". In one Old English work, cucumbers are called eorþæppla (lit. "earth-apples'), just as in French, Dutch, Hebrew, Persian and Swiss German, the words for potatoes mean "earth-apples" in English. In some languages, oranges are called "golden apples" or "Chinese apples". Datura is called 'thorn-apple".

Ethnobotanical and ethnomycological scholars such as R. Gordon Wasson, Carl Ruck and Clark Heinrich write that the mythological apple is a symbolic substitution for the entheogenic Amanita muscaria (or fly agaric) mushroom. Its association with knowledge is an allusion to the revelatory states described by some shamans and users of psychedelic mushrooms. At times artists would co-opt the apple, as well as other religious symbology, whether for ironic effect or as a stock element of symbolic vocabulary. Thus, secular art as well made use of the apple as symbol of love and sexuality. It is often an attribute associated with Venus who is shown holding it.

The apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family (Rosaceae). It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apples grow on small, deciduous trees. The tree originated in Western Asia, where its wild ancestor, Malus sieversii, is still found today. Apples have been grown for thousands of years in Asia and Europe, and were brought to North America by European colonists. Apples have been present in the mythology and religions of many cultures, including Norse, Greek and Christian traditions. In 2010, the fruit's genome was decoded, leading to new understandings of disease control and selective breeding in apple production.

There are more than 7,500 known cultivars of apples, resulting in a range of desired characteristics. Different cultivars are bred for various tastes and uses, including in cooking, fresh eating and cider production. Domestic apples are generally propagated by grafting, although wild apples grow readily from seed. Trees are prone to a number of fungal, bacterial and pest problems, which can be controlled by a number of organic and non-organic means.