Here i have explained how to get Exception Message in Ajax Method using jQuery in Asp.Net C#.
Here i have explained how to use AsyncFileUpload control and how to clear it (file upload control) if the file is uploaded using Ajax in Asp.Net C#.
Here i have explained how to Install AjaxControlToolkit in Asp.Net.
What is AJAX?
AJAX allows web pages to be updated asynchronously by exchanging data with a web server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page.