When you dragged the Button and the TextBox from the Toolbox on the page in Design View, VS
added the corresponding code for you in Markup View automatically. Similarly, when you changed the
Text property of the button in the Properties Grid, VS automatically updated the markup for the control
in Markup View. Instead of using the Properties Grid, you could also have typed the text directly
between the quotation marks of the Text property in Markup View.
After changing the Text property, your page should contain this code in Markup View: