A nursery rhyme is a traditional song or poem taught to young children, originally in the nursery. Learning such verse assists in the development of vocabulary, and several examples deal with rudimentary counting skills. ("Eeny, meeny, miny, moe" is an example of a counting-out game.) In addition, specific actions, motions, or dances are often associated with particular songs.
Some nursery rhymes, however, are substantially older. "Sing a Song of Sixpence" exists in written records as far back as the Middle Ages. Arguably the most famous collection of nursery rhymes is that of Mother Goose. Some well known nursery rhymes originated in the United States, such as "Mary had a little lamb".
The nursery rhyme "Ring a Ring O'Roses" is popularly believed to be a metaphorical reference to the Great Plague of London, although this has been widely discredited, particularly as none of the "symptoms" described by the poem even remotely correlate to those of the bubonic plague, and the first record of the rhyme's existence was not until 1881.
An amusing and ironic accidental hoax involving the rhyme "Sing a Song of Sixpence" was perpetrated on the Urban Legends Reference Pages.
There are some indigenous peoples which consider music sacred, so that only elder men may sing songs, and the songs are taught during sacred rituals in adulthood. It is forbidden for women or children to sing. Hence, these cultures do not have these kinds of songs.

Twinkle, Twinkle, Little Star is one of the most popular English nursery rhymes. It combines the tune of the 1761 French melody "Ah ! vous dirai-je, Maman" with an English poem, "The Star", by Jane Taylor. The poem, which is in couplet form, was first published in 1806 in Rhymes for the Nursery, a collection of poems by Taylor and her sister Ann.

Twinkle, twinkle, little star,
How I wonder what you are!
Up above the world so high,
Like a diamond in the sky.
Twinkle, twinkle, little star,
How I wonder what you are!

When the blazing sun is gone,
When he nothing shines upon,
Then you show your little light,
Twinkle, twinkle, all the night.
Twinkle, twinkle, little star,
How I wonder what you are!
Then the traveler in the dark,
Thanks you for your tiny spark,
He could not see which way to go,
If you did not twinkle so.
Twinkle, twinkle, little star,
How I wonder what you are!
In the dark blue sky you keep,
And often through my curtains peep,
For you never shut your eye,
Till the sun is in the sky.
Twinkle, twinkle, little star,
How I wonder what you are!
As your bright and tiny spark,
Lights the traveller in the dark,—
Though I know not what you are,
Twinkle, twinkle, little star.
Twinkle, twinkle, little star,
How I wonder what you are!


The full version of bla bla black sheep

Baa, baa, black sheep,
Have you any wool?
Yes sir, yes sir,
Three bags full.
One for the master,
One for the dame,
And one for the little boy
Who lives down the lane.
An occasionally used second verse is:

Thank you said the master,
Thank you said the dame,
Thank you said the little boy
Who lives down the lane.