Ajax is a technology used to improve user experience. Its essence is to use a special object (XMLHttpRequest) built in the browser asynchronously (that is, when sending a request, the browser will not destroy the current page, and the user can continue to do things on the current page. Other operations) send a request to the server, and use the data returned by the server (no longer a complete page, just partial data, usually returned using text or xml) to partially update the current page.
After using ajax technology, the page does not refresh and does not interrupt the user's operation. Interested friends can come and take a look