Ordering is the process of finding the position of an element of ordinal data type in a sequence.
Order and Equivalence are a special kind of binary relation (ie relation between two entities)
With the order notion, you get immediately a sort and merge problem.
Comparison operator are at the heart of sort and merge problem problem.
Natural order is the default attribute of a data type that will drive the sort process.
For instance, if you have a person object representing a person and if the default sort attribute is define to be by name, the natural order of the person object is by name. If you sort a collection of person without any specification, they will be sorted by natural order, ie by name.