Ajax is a web development technique for creating interactive web applications. The AJAX has many states.
It is very important part of AJAX terminology in web development aspect.

There are following state in AJAX

0: This state represent request is uninitialized.(before you’ve called open() method in ajax request).
1: This state represent request is set up, but not sent (before you’ve called send() method).
2: This state represent request was sent and is in process (you can get content headers from response).
3: This state represent request is in process (In this Ajax state normally some partial data is available but the server isn’t completed Ajax request yet.
4: This state represent requested has been completed.(Response is now available).