title: What is data-bound properties?
body: <p>I am trying to understand OnInit functionality in angular2 and read the documentation: </p>
  
  <blockquote>
    <p>Description</p>
    
    <p>Implement this interface to execute custom initialization logic after
    your directive's data-bound properties have been initialized.</p>
    
    <p>ngOnInit is called right after the directive's data-bound properties
    have been checked for the first time, and before any of its children
    have been checked. It is invoked only once when the directive is
    instantiated.</p>
  </blockquote>
  
  <p>I do not understand <code>directive's data-bound properties</code> what does it mean? </p>