Method extension in VS2008 and VS2010

We are used to use the static method of the class.

public class CommonClass
{
        public CommonClass
        {

        } 
        public static string ReverseString(string stringToReverse)
        {
                //Code to reverse the string
        }
        
}

Calling the static method.

MessageBox.Show(CommonClass.ReverseString("DotNetFunda"));

Now, we move to method extension

public static class ExtensionClass
{
          public static string ReverseString(this string str)
          {
                  //Code to reverse the string
          }
}

Calling

MessageBox.Show("DotNetFunda".ReverseString());