title: What is the difference between a User Control Library and a Custom Control Library?
body: <p>I am just coming up to speed on WPF and would like to create a reusable WPF control.  </p>
  
  <p>When I look at the options for creating projects in Visual Studio, I see "WPF User Control Library" and "WPF Custom Control Library".  It's unclear to me what the difference is between them and my Google searches have not turned up any decent explanations.</p>
  
  <p>I'd like to understand the differences between them and ideally see some examples of when to use one over the other.</p>