title: What are in SQL Server User Instances that make them impossible in non-Express Editions?
body: <p>After developing for a few years (or more), I still do not understand:  </p>
  
  <ul>
  <li>What makes User Instances impossible/incompatible with Developer (or any other) edition of SQL Server?    
  
  <ul>
  <li>Why has developer to install more than one (i.e. developer edition) of SQL Server because user instances are available only through Express Edition?   </li>
  </ul></li>
  </ul>
  
  <p>Update: @Damien_The_Unbeliever wrote in his answer,  </p>
  
  <p><a href="https://stackoverflow.com/questions/4183485/what-are-in-sql-server-user-instances-that-make-them-impossible-in-non-express-ed/4183544#4183544">"User instances are pretty well expected to be standalone databases, only used by a single application, and meaningless without that application."</a>  </p>
  
  <p>Do I understand correctly that user instances:   </p>
  
  <ul>
  <li>require SQL Server Express setup</li>
  <li>cannot be connected remotely</li>
  <li>the user cannot have more than one such instance?  </li>
  <li>the client apps that connect to them are dev tools like VS, SSMS, webadmin, <a href="http://www.microsoft.com/downloads/en/details.aspx?FamilyID=fa87e828-173f-472e-a85c-27ed01cf6b02&amp;DisplayLang=en" rel="nofollow noreferrer">SQL Express Utility</a>, etc?  </li>
  </ul>
  
  <p>Really I do not understand when/why/how they can be used/deployed outside of development environment</p>
  
  <p><a href="https://stackoverflow.com/questions/4184746/what-are-the-non-dev-cases-of-sql-server-user-instances-vs-ce-and-other-embedded">What are the non-dev cases of SQL Server User Instances (vs CE and other embedded databases)?</a></p>