title: What is difference between extension method and static method?
body: <p>What is the difference between an extension method and a static method ?</p>
  
  <p>I have two classes like this :</p>
  
  <pre><code>public static class AClass {
      public static int AMethod(string ....)
      {
      }
  }
  </code></pre>
  
  <p>and</p>
  
  <pre><code>public static class BClass {
      public static int BMethod(this string ....)
      {
      }
  }
  </code></pre>
  
  <p>I can use these like</p>
  
  <pre><code>AClass.AMethod('...');
  </code></pre>
  
  <p>or</p>
  
  <pre><code>'...'.BMethod();
  </code></pre>
  
  <p>Which is proposed ?</p>