A barn raising, also historically called a raising bee or rearing in the U.K., is a collective action of a community, in which a barn for one of the members is built or rebuilt collectively by members of the community. Barn raising was particularly common in 18th- and 19th-century rural North America. A barn was a necessary structure for any farmer, for example for storage of cereals and hay and keeping of animals. Yet a barn was also a large and costly structure, the assembly of which required more labor than a typical family could provide. Barn raising addressed the need by enlisting members of the community, unpaid, to assist in the building of their neighbors' barns. Because each member could ask others for help, reciprocation could eventually reasonably be presumed for each participant if the need were to arise.

A barn is an agricultural building usually on farms and used for various purposes. In North America, a barn refers to structures that house livestock, including cattle and horses, as well as equipment and fodder, and often grain. As a result, the term barn is often qualified e.g. tobacco barn, dairy barn, cow house, sheep barn, potato barn. In the British Isles, the term barn is restricted mainly to storage structures for unthreshed cereals and fodder, the terms byre or shippon being applied to cow shelters, whereas horses are kept in buildings known as stables. In mainland Europe, however, barns were often part of integrated structures known as byre-dwellings. In addition, barns may be used for equipment storage, as a covered workplace, and for activities such as threshing.