title: What is the point of a Data Transfer Object (DTO)?
body: <p>Why should I use DTOs/Domain objects when I can just put all business classes in a class library, use them in the business logic, then also pass those same business objects on to boundary classes?</p>
  
  <p>UPDATE:
  All are great points, thanks for the help.  A follow up question:</p>
  
  <p>Where do you typically place these DTOs?  Alongside the Domain objects i.e. in the same namespace?</p>
  
  <pre><code>namespace MedSched.Medical
  {
      public class MedicalGroup
      {
          //...
      }
  
      public class MedicalGroupDTO
      {
          //...
      }
  }
  </code></pre>