title: how does PropertyChangedEventHandler work?
body: <p>This is a really simple question, but I was wondering if someone could explain what the 4th line is actually doing? so the first line gives an event to the handler. I don't really know in what circumstances handler will return null or what the last line does.</p>
  
  <p>When you pass the handler your object and which property changed, what does it do with them?</p>
  
  <pre><code>PropertyChangedEventHandler handler = PropertyChanged; //property changed is the event
  
  if (handler != null)
  {
      handler(this, new PropertyChangedEventArgs(name));
  }
  </code></pre>
  
  <p>I assume I used this to get this <a href="http://msdn.microsoft.com/en-us/library/system.componentmodel.inotifypropertychanged.aspx" rel="noreferrer">code</a> but I would like to understand what it is doing fully.</p>