Common cuckoo in the context of "Cuculiformes"

Cuckoos are birds in the Cuculidae (/kjuːˈkjuːlɪdiː/ kew-KEW-lih-dee) family, the sole taxon in the order Cuculiformes (/kjuːˈkjuːlɪfɔːrmiːz/ kew-KEW-lih-for-meez). The cuckoo family includes the common or European cuckoo, roadrunners, koels, malkohas, couas, coucals, and anis. The coucals and anis are sometimes separated as distinct families, the Centropodidae and Crotophagidae, respectively. The cuckoo order Cuculiformes is one of three that make up the Otidimorphae, the other two being the turacos and the bustards. The family Cuculidae contains 150 species, which are divided into 33 genera.

The cuckoos are generally medium-sized, slender birds. Most species live in trees, though a sizeable minority are ground-dwelling. The family has a cosmopolitan distribution; the majority of species are tropical. Some species are migratory. The cuckoos feed on insects, insect larvae, and a variety of other animals, as well as fruit. Some species (for example, the majority of cuckoo species living in Eurasia) are brood parasites, laying their eggs in the nests of other species and giving rise to the terms "cuckoo's egg" and "cuckold" as metaphors. However, most species raise their own young.

The term cuckoo's egg is a metaphor for brood parasitism, where a parasitic bird deposits its egg into a host's nest, which then incubates and feeds the chick that hatches, even at the expense of its own offspring. That original biological meaning has been extended to other uses, including one which references spyware and other pieces of malware.

A cuckoo clock is a type of clock, typically pendulum driven, that strikes the hours with a sound like a common cuckoo call and has an automated cuckoo bird that moves with each note. Some move their wings and open and close their beaks while leaning forwards, whereas others have only the bird's body leaning forward. The mechanism to produce the cuckoo call has been in use since the middle of the 18th century and has remained almost without variation.

It is unknown who invented the cuckoo clock and where the first one was made. It is thought that much of its development and evolution was made in the Black Forest area in southwestern Germany (in the modern state of Baden-Württemberg), the region where the cuckoo clock was popularized and from where it was exported to the rest of the world, becoming world-famous from the mid-1850s on. Today, the cuckoo clock is one of the favourite souvenirs of travellers in Germany, Switzerland, Austria and eastern France. It has become a cultural icon of Germany.

Edward Jenner (17 May 1749 – 26 January 1823) was an English physician and scientist who pioneered the concept of vaccines and created the smallpox vaccine, the world's first vaccine. The terms vaccine and vaccination are derived from Variolae vaccinae ('pustules of the cow'), the term devised by Jenner to denote cowpox. He used it in 1798 in the title of his Inquiry into the Variolae vaccinae known as the Cow Pox, in which he described the protective effect of cowpox against smallpox.

Jenner is often called "the father of immunology", and his work is said to have saved "more lives than any other man". In Jenner's time, smallpox killed around 10% of the global population, with the number as high as 20% in towns and cities where infection spread more easily. In 1821, he was appointed physician to King George IV, and was also made mayor of Berkeley and justice of the peace. He was a member of the Royal Society. In the field of zoology, he was among the first modern scholars to describe the brood parasitism of the cuckoo (Aristotle also noted this behaviour in his History of Animals). In 2002, Jenner was named in the BBC's list of the 100 Greatest Britons.