 <p>The second option allows you to do more complex formatting. With a <code>string</code>, there is little advantage, but if you were using a <code>double</code> value, for example, you could use the <a href="http://msdn.microsoft.com/en-us/library/txafckwd%28v=vs.110%29.aspx" rel="nofollow">composite format options</a> to specify the amount of precision to display or other options.</p>