title: What is the purpose of partial classes?
body: <p>I read <a href="http://msdn.microsoft.com/en-gb/library/wa80x488%28v=vs.100%29.aspx" rel="noreferrer">about partial classes</a> and, for example, I understand the reason for they are used when Visual Studio creates Windows Forms, without ruling out that </p>
  
  <blockquote>
    <p>when working on large projects, spreading a class over separate files
    enables multiple programmers to work on it at the same time</p>
  </blockquote>
  
  <p>.</p>
  
  <p>Later I read <a href="http://www.csharpcourses.com/2008/05/multi-tier-sample-code-best-practice.html" rel="noreferrer">this example</a> and I noticed that most of the classes are declared as partial. Why?</p>