You can use this property to determine if the user has modified the contents of the text box control. You can also set this property in code to indicate that changes were made to the text box control by the application. This property can be used by validation and data-saving methods to determine if changes were made in a text box control so the changed contents can be validated or saved.

If you change the TextBoxBase.Text property programmatically, the TextBoxBase.Modified property reverts to false. This does not raise the TextBoxBase.ModifiedChanged event.