The term "nursery rhyme" refers to a traditional song or poem for children, such as "Ring around the Rosie" or 'Remember Remember'. "Nursery rhyme" is a British phrase, but its equivalents, such as "Mother Goose Rhymes," are found in many cultures.
Usage of the term "nursery rhyme" dates back to 18th century England, but traditional poems and rhymes for children are staples of many cultures. The oldest childrens' songs of which historians have records are lullabies, songs sung to children to help them sleep. Lullabies are found in every human culture, though they do not always feature words and are more akin to melodies put to simple syllables. The melodies of lullabies were eventually put to more complex rhyme schemes and written down, and thus the nursery rhyme was born.
Nursery rhymes, especially those of 18th- and 19th-century Britain, are infamous for their dark subject material, made more frightening by their innocent-sounding melodies. "Remember, Remember" is a rhyme about the attempted assassination of King James I at the hands of pro-Catholic terrorists, and it is taught to British children to this day.
Other examples of common nursery rhymes include "Baa, Baa Black Sheep," "Little Miss Muffet" and "Three Blind Mice."