Introdution.

What is reference couting?

Reference counting is a technique that is used when you need to maintain several references to a same place, or more concretely to the same object without having to have several copies of this object in memory.

The derived problem to make reference to an object from several places appears when you no longer has need of the object, that is to say, determining the moment the memory of the object should be released. This does not constitute a problem in languages with a good garbage collector (as C#) but can suppose an enormous source of memory leaks in other projects. For example, suppose that have something like this (the code is in C++ but it is almost equal in Delphi)