Callbacks: how to make and use them

Hi,
What is a callback function and how do we make and use them?
Many thanks,
Lau

Does this have anything to do with Javascript? Have you tried Google?

http://en.wikipedia.org/wiki/Callback_(computer_science)

http://www.codeguru.com/cpp/cpp/cpp_mfc/callbacks/article.php/c10557

http://www.velocityreviews.com/forums/t291572-what-is-callback-function.html