title: Why escape brackets (curly braces) in a format string in .NET is '{{' or '}}" not '\{' or '\}'
body: <p>There is  a question <a href="https://stackoverflow.com/questions/91362/how-to-escape-brackets-curly-braces-in-a-format-string-in-net">how-to-escape-brackets-curly-braces-in-a-format-string-in-net</a> but There none to describe the reason? why is using <code>{{</code> or <code>}}</code> not <code>\{</code> or <code>\}</code>. </p>
  
  <p>eg.    <code>string s = String.Format("{{ hello to all }}")</code>;
   why not using <code>\{</code> like  string escape in string such as:    <code>\b\n\t</code></p>
  
  <p>**I want to know the deepin reason  or from the language design **</p>