From http://www.w3schools.com (Copyright Refsnes Data)

ASP .NET - The TextBox Control

The TextBox control is used to create a text box where the user can input text.

The TextBox Control

The TextBox control is used to create a text box where the user can input text.

The TextBox control's attributes and properties are listed in our web controls reference page.

The example below demonstrates some of the attributes you may use with the TextBox control:

Example

<html>
<body>

<form runat="server">

A basic TextBox:
<asp:TextBox id="tb1" runat="server" />
<br /><br />

A password TextBox:
<asp:TextBox id="tb2" TextMode="password" runat="server" />
<br /><br />

A TextBox with text:
<asp:TextBox id="tb4" Text="Hello World!" runat="server" />
<br /><br />

A multiline TextBox:
<asp:TextBox id="tb3" TextMode="multiline" runat="server" />
<br /><br />

A TextBox with height:
<asp:TextBox id="tb6" rows="5" TextMode="multiline"
runat="server" />
<br /><br />

A TextBox with width:
<asp:TextBox id="tb5" columns="30" runat="server" />

</form>

</body>
</html>

Add a Script

The contents and settings of a TextBox control may be changed by server scripts when a form is submitted. A form can be submitted by clicking on a button or when a user changes the value in the TextBox control.

In the following example we declare one TextBox control, one Button control, and one Label control in an .aspx file. When the submit button is triggered, the submit subroutine is executed. The submit subroutine writes a text to the Label control:

<script runat="server">
Sub submit(sender As Object, e As EventArgs)
lbl1.Text="Your name is " & txt1.Text
End Sub
</script>

<html>
<body>

<form runat="server">
Enter your name:
<asp:TextBox id="txt1" runat="server" />
<asp:Button OnClick="submit" Text="Submit" runat="server" />
<p><asp:Label id="lbl1" runat="server" /></p>
</form>

</body>
</html>

Example

In the following example we declare one TextBox control and one Label control in an .aspx file. When you change the value in the TextBox and either click outside the TextBox or press the Tab key, the change subroutine is executed. The submit subroutine writes a text to the Label control:

<script runat="server">
Sub change(sender As Object, e As EventArgs)
lbl1.Text="You changed text to " & txt1.Text
End Sub
</script>

<html>
<body>

<form runat="server">
Enter your name:
<asp:TextBox id="txt1" runat="server"
text="Hello World!"
ontextchanged="change" autopostback="true"/>
<p><asp:Label id="lbl1" runat="server" /></p>
</form>

</body>
</html>

Example