title: UserId string comparison within ASP.NET Identity
body: <p>I am using ASP.NET identity in MVC 5 and wondered the best way to perform string comparison during say, a query to a table where records have been entered with the userId as an foreign key.</p>
  
  <p>Normally I would just plump for <code>==</code> but I wasn't sure how the string for a userId inside .NET identity is created. 
  I guess it's actually a GUID of sorts under the hood so I'd presume that <code>==</code> would be fine but I wondered if the culture or case would come into it at all.</p>
  
  <p>Does anyone know if the string is a unique GUID for <code>==</code> type comparison, or should I be using <code>string.Equals</code> and some <code>StringComparison</code> option to account for cultures?</p>