"Itsy Bitsy Spider" (also known as "Incy Wincy Spider" or "Eency Weency Spider" or "Ipsy Wispy Spider" or "Ipsy Dipsy Spider") is a popular nursery rhyme that describes the adventures of a spider as it ascends, descends and reascends the downspout or "waterspout" of a gutter system (or, alternatively, the spout of a teapot). It is usually accompanied by a sequence of gestures that mimic the words of the song. It has a Roud Folk Song Index number of 11586.

There are various versions of the lyrics:

The itsy bitsy spider went up the water spout.

Down came the rain, and washed the spider out.

Up came the sun, and dried up all the rain,

and the itsy bitsy spider went up the spout again.

(Some versions have climbed or crawled instead of went.)
The Itsy Bitsy Spider or The Eensy Weensy Spider is sometimes chanted rather than sung. Recitation of the rhyme is often combined with fingerplays representing the words. For the first (and last) line, alternately touch the thumb of one hand to the index finger of the other. For "Down came the rain" hold both hands up and wiggle the fingers as you lower the hands. For "washed the spider out" sweep the hands to the side. For the third line bring both hands up and then to the sides to sweep out a semicircle (the sun). Then wiggle the fingers upwards (to show the rain drying in the sun), and repeat the thumb/index finger movement to indicate the spider climbing up the spout.
An alternative version is:

Incy Wincy spider climbing up the spout.

Down came the rain, and washed poor Incy out.

Up came the sun, and dried up all the rain

And Incy Wincy spider went climbing up again.

Origins

The song can be found in publications including an alternate version in the book, Camp and Camino in Lower California (1910).It was published in its modern version in Western Folklore, by the California Folklore Society (1947),Mike and Peggy, Seeger's, American Folk Songs for Children (1948), and The Growing Family: A Guide for Parents by Maxwell Slutz Stewart (1955).