All server controls must appear within a <form> tag, and the <form> tag must contain the runat="server" attribute. The runat="server" attribute indicates that the form should be processed on the server and it also indicates that the enclosed controls can be accessed by server scripts

Note: The form is always submitted to the page itself and if you specify an action attribute, it is ignored. If you omit the method attribute,it will be set to method="post" by default. Also,they are automatically assigned by ASP.NET,if you do not specify the name and id attributes.

Note: An .aspx page can only contain ONE <form runat="server">control! You will see that ASP.NET has added these attributes to the form,if you select view source in an .aspx page containing a form with no name, method, action, or id attribute specified. It looks something like this:

A form is most often submitted by clicking on a button and the Button server control in ASP.NET has the following format:

The id attribute defines a unique name for the button and the text attribute assigns a label to the button and the onClick event handler specifies a named subroutine to execute.

In an .aspx file,in the following example we declare a Button control. A button click runs a subroutine which can change the text on the button: