Taken from: [link]
The paper crane has become an international symbol of peace in recent years as a result of it's connection to the story of a young Japanese girl named Sadako Sasaki born in 1943. Sadako was two years old when the atom bomb was dropped on Hiroshima, Japan on August 6, 1945. As she grew up, Sadako was a strong, courageous and athletic girl. In 1955, at age 11, while practicing for a big race, she became dizzy and fell to the ground. Sadako was diagnosed with Leukemia, "the atom bomb" disease.
Sadako's best friend told her of an old Japanese legend which said that anyone who folds a thousand paper cranes would be granted a wish. Sadako hoped that the gods would grant her a wish to get well so that she could run again. She started to work on the paper cranes and completed over 1000 before dying on October 25, 1955 at the age of twelve.
The point is that she never gave up. She continued to make paper cranes until she died.
Inspired by her courage and strength, Sadako's friends and classmates put together a book of her letters and published it. They began to dream of building a monument to Sadako and all of the children killed by the atom bomb. Young people all over Japan helped collect money for the project.
In 1958, a statue of Sadako holding a golden crane was unveiled in Hiroshima Peace Park. The children also made a wish which is inscribed at the bottom of the statue and reads:
"This is our cry, This is our prayer, Peace in the world".
Today, people all over the world fold paper cranes and send them to Sadako's monument in Hiroshima.