RadTextBox is an input control that lets the user enter text. By default, the TextMode property of the control is set to InputMode.SingleLine, which displays a single-line text box. However, you can also use RadTextBox to display a multiline text box or a text box that masks user input by changing the value of the RadTextMode property to InputMode.MultiLine or InputMode.Password, respectively.

The text displayed in RadTextBox is specified or determined by using the Text property. Additionally, the Skin property allows you to control the appearance.

The display width of the text box (in characters) is specified by its Columns property. If RadTextBox is a multiline text box, the number of rows it displays is defined by the Rows property. To render text that wraps within the RadTextBox control, set the Wrap property to true.

You can also specify how data is entered in RadTextBox by setting a few properties. To prevent the text from being modified, set the ReadOnly property to true. If you want to limit the user input to a specified number of characters, set the MaxLength property to the desired integer value.

Finally, the purpose of the EmptyMessage is to provide more information for the user about the RadTextBox itself without cluttering up the rest of the page.