Okay kiddo, so imagine you need to ask your Mom for a cookie. Normally, you would go up to her and say "Mom, can I have a cookie?" and she would give you one.
But with Ajax, it's like you sending your Dad to ask Mom for a cookie without you having to leave your room.
In computer terms, Ajax stands for "Asynchronous JavaScript and XML." It's a way for web pages to communicate with the server in the background without having to reload the entire page.
So when you click a button or fill out a form on a web page, instead of the whole page reloading, only certain parts of the page (like a pop-up or a message that says "success!") will change. This makes the website feel faster and more responsive.
So think of Ajax like a messenger boy that goes back and forth between your computer and the server, bringing and receiving information without the whole page having to reload. Pretty cool, huh?