This variable can be written on html element like div element. Traditional ajax is basically a network call.
We can use ajax network call technique to populate combo box or select element from database, Auto complete function, search records, update, insert record etc.
Remember that we have to put ScriptManager control in aspx page to enable Asp.Net ajax extension.
Web Request Example
I have two textboxes which their ids are txname and txage. After user enters his/her name, age and clicks “Go” button, current date and time will be displayed in div element along with entered values in each textboxes.