title: Choosing the correct C# collection to use
body: <p>I have an object that contains a list of child objects.
  This is a very simple Order -> OrderLines type of relationship.</p>
  
  <p>Now I'm trying to map out my class and have set up the object as an ICollection:</p>
  
  <pre><code>public virtual ICollection&lt;OrderLines&gt; OrderLinesCollection { get; set; }
  </code></pre>
  
  <p>However when I assign values to the collection, I am unsure on whether to use a HashSet or a List to hold my collection of OrderLines.</p>
  
  <pre><code>this.OrderLinesCollection = new HashSet&lt;OrderLines&gt;();
  this.OrderLinesCollection = new List&lt;OrderLines&gt;();
  </code></pre>
  
  <p>What is the best way of doing this?</p>