<p><code>Html.TextBox("ParentPassword", "", new { @class = "required" })</code></p>

<p>what the gosh darned heck is the @ for the @class.</p>

```
class
```
is a reserved keyword, so you can't use this as a variable name.
The @ operator allows you to get around this rule.  The reason why its being done here is that the anonymous object is used to populate attributes on a HTML element.  A valid attribute name is "class", which lets you set the CSS class on the element.