Question: How do I fill a textbox with text if it is empty? I am using VB.NET.

Answer: 
You will probably want to handle the `TextChanged` event and set some default text if the text box is empty when the event is fired.

I don't have a VB.NET example, but the following C# should be too hard to understand:

```
public Form1()
{
    this.InitializeComponent();

    textBox1.Tag = "Default text";
    textBox1.Text = (string)textBox1.Tag;
    textBox1.TextChanged += new EventHandler(OnTextChanged);
}

void OnTextChanged(object sender, EventArgs e)
{
    var textbox = (TextBox)sender;

    if (string.IsNullOrEmpty(textbox.Text))
    {
        textbox.Text = (string)textbox.Tag;
    }
}

```

And the event handler can be reused for several text boxes.

**EDIT:** Here's pretty much the same in VB.NET

```
Sub New()
    ' This call is required by the designer.
    InitializeComponent()

    TextBox1.Tag = "Default text"  ' This can be set with the designer
    TextBox1.Text = CStr(TextBox1.Tag)
End Sub

Private Sub OnTextBoxTextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
    Dim textbox As TextBox = DirectCast(sender, TextBox)

    If String.IsNullOrEmpty(textbox.Text) Then
        textbox.Text = CStr(textbox.Tag)
        textbox.SelectAll()
    End If
End Sub

```

Of course, you can also achieve similar behavior using native Windows functionality, but a few lines of managed code will give you pretty much all you need even if you do not want to use Win32.
I assume you meant to add text from the aspx page.

```
<asp:TextBox ID="TextBox1" runat="server" value="Default Value"></asp:TextBox

```

Even when .NET don't suggest this feature in the intellitext, I assume that it will allow you to put any attribute, even custom that you can manipulate data in it. But, it does the work. and the value attribute is sent to the browser, therefore, initiate in the text field.

For TextArea (TextMode="MultiLine"), you can put between the tags.

```
<asp:TextBox ID="TextBox1" runat="server" TextMode="MultiLine">Text Here will be inside the TextArea</asp:TextBox>

```

It is like html textarea tag behave.