For the first two TextBlock controls, the UI will have a plain text on it. The third TextBlock control will have Bold, Italic, and Underline applied to it, by specifying the FontWeight, FontStyle, and TextDecoration properties of the control. Also, the foreground color of it has been set to red, by specifying the Foreground property.
You can also set a different font to your TextBlock control. Use the FontFamily property to set it. As you can see, the fourth TextBlock control has a Lucida Handwriting font applied to it.
When you have a long text, which is not viewable in a single line, you can either wrap it to multiline or trim it, based on the available space. TextWrapping="Wrap", in the fifth TextBlock spans it to multiline. Try making the window bigger or smaller, and you will see that the TextBlock automatically adjusts itself to match the available space, whereas, the text of the sixth TextBlock control trims with the TextTrimming property set to character...