A delta is a landform that is formed at the mouth of a river, where that river flows into an ocean, sea, estuary, lake, or reservoir. Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river. Over long periods of time, this deposition builds the characteristic geographic pattern of a river delta.

Contrary to popular belief, the term delta was not coined by Herodotus.

Alexandra Marguerite Clémentine Cousteau (born March 21, 1976) is the daughter of Philippe Cousteau and the granddaughter of world famous French explorer and filmmaker Jacques-Yves Cousteau. A dedicated environmentalist, Cousteau advocates the importance of conservation, restoration and sustainable management of water resources for a healthy planet and productive societies.

A member of the third generation of the Cousteau family to devote their lives to exploring and explaining the natural world, Cousteau first went on expedition with her father, Philippe Cousteau, when she was four months old, and learned to scuba dive with her grandfather, Jacques-Yves Cousteau, when she was seven. She grew up traveling the globe, developed a passion for adventure and learned firsthand the value of conserving the natural world. Of her father and grandfather, Cousteau says, "The best example they gave me was the importance of living a life of consequence, value, and meaning. I honor their memories by creating a legacy of my own in speaking out for the preservation of our blue planet and all its waters."

The PS22 Chorus is an elementary school chorus from Public School 22 in Graniteville, Staten Island (New York). It is composed of 60-70 fifth-graders, and is directed by Gregg Breinberg. Students are assigned to the chorus after an annual auditioning process at the beginning of each school year. PS22 is the largest elementary school in Staten Island which draws students from a wide cross section of ethnic groups and socio-economic levels. The chorus meets twice a week during school hours to practice, and performs throughout the year at school functions, local events, and on special requests. It has been featured on several major national news and music networks after its videos had gained international attention within the popular video-sharing site YouTube. To date, the chorus’s videos have been watched more than 45,000,000 times.

The PS22 chorus was founded in 2000 by the school's music teacher, Gregg Breinberg, who started blogging about it in September 2006 following requests on a Tori Amos fan page, where he had shared some of his videos. Since then the chorus has become an Internet phenomenon. In 2009 New York magazine called it "the best-known elementary-school chorus on the planet".