System.Collections.IComparer

Added in .NET 1.1
When you implement the IComparer there are two steps.
First declare a class that implements IComparer

private class SortAscendingHelper : System.Collections.IComparer 
{ 
   int IComparer.Compare(object a, object b) 
   { 
      myobject = my1 (myObject)a; 
      myobject = my2 (myObject)b; 
      if (my1.MySortProperty > my2.MySortProperty) 
      { 
         return 1; 
      } 
      if (my1.MySortProperty < my2.MySortProperty) 
      { 
         return -1; 
      } 
      return 0; 
   } 
} 

Second implement the Compare method.

public static System.Collections.IComparer sortAscending() 
{ 
   return (IComparer) new SortAsecendingHelper(); 
} 

System.IComparable

Added in .NET 1.1
System.IComparable
Provides a comparer check (for sorting) when there is only one way of ordering the objects (implemented inside the class)