What's a sync and async method?
<p>What's a sync method and what is an async method ? What's the difference between sync and async methods ? When do I have to use sync or async method ?
I'm asking those questions because I don't understand :</p>

<pre><code>public async void ReadData(filepath)
{
    CreateDoc("hello");    //&lt;------ Why I can't do that ?
}

public void CreateDoc(string astring)
{
    Debug.WriteLine(astring);
}
</code></pre>

<p>And why I can't do that ? :</p>

<pre><code>public async void ReadData(filepath)
{
     var BarreDroite = new string[] { "|" };
     foreach (string tableArret in items.Split(BarreDroite, StringSplitOptions.RemoveEmptyEntries))
     {
         listeArret.Add(tableArret); //&lt;---- Here appear the problem.
     }
{
</code></pre>

<p>I ask this question because I don't really find clear explanations on the web.</p>