TextBlock

<TextBlock FontSize="36"
TextWrapping="Wrap">
This is
some <Run FontWeight="Bold">bold</Run> text and
some <Run FontStyle="Italic">italic</Run> text and
some <Run Foreground="Red">red</Run> text and
some <Run TextDecorations="Underline">underlined</Run> text
and some <Run FontWeight="Bold"
FontStyle="Italic"
Foreground="Cyan"
FontSize="72"
TextDecorations="Underline">big</Run> text. </TextBlock>