AJAX is a word composed of the terms »asynchronous«, »JavaScript«, and »XML« and refers to the process of transferring data between a web server and a web browser not simultaneously but asynchronously. It’s made possible by using JavaScript’s XMLHttpRequest and the specialty of this technique is that the communication takes place in the background and not originating directly from the user. In doing so, it’s possible to modify data remotely and update pages so that the user can continue to interact with an interface seamlessly and it doesn’t need to be reloaded using traditional full-page refreshing but works with partial page updates.
Example: A user is entering their address data in an application and the browser is already communicating with the server to check the validity of the full address or portions the postal code. This results in shorter/faster processing times for the user and there is no need to wait for a response from the server.