Whats the main function of Ajax?? And when we must using Ajax on web programming?

Question

I've hear about Ajax, but dont know what is it, and when to use it.

Answer 1

Ajax is a client-side script that communicates to and from a server/database without the need for a postback or a complete page refresh. The best definition I've read for Ajax is “the method of exchanging data with a server, and updating parts of a web page – without reloading the entire page.

Use:
Ajax ( "Asynchronous JavaScript And XML") is a set of Web development techniques using many Web technologies on the client side to create asynchronous Web applications.