Hoopoes are colourful birds found across Africa, Asia, and Europe, notable for their distinctive "crown" of feathers which can be raised or lowered at will. Three living and one extinct species are recognized, though for many years all of the extant species were lumped as a single species—Upupa epops. In fact, some taxonomists still consider all three species conspecific. Some authorities also keep the African and Eurasian hoopoe together but split the Madagascar hoopoe. The Eurasian hoopoe is common in its range and has a large population, so it is evaluated as Least Concern on The IUCN Red List of Threatened Species. However, their numbers are declining in Western Europe. Conversely, the hoopoe has been increasing in numbers at the tip of the South Sinai, Sharm el-Sheikh. There are dozens of nesting pairs that remain resident all year round.

The crest is a prominent feature exhibited by several bird and other dinosaur species on their heads. It is distinct from features such as casques and cockscombs - sometimes erroneously referred to as "crests", which are bony and fleshy structures respectively.