Hierarchical data appears everywhere and most of the time it must be rebuilt from simple non-hierarchical storage. Think about mail, news, CVS repositories and databases, not to mention groupware and chat forums. Trees are everywhere.
- Put It In A Tree, The Delphi Magazine 118, June 2005
This article dealt with thread sorting, an algorithm that takes a number of items connected with parent-child relationship and puts them into a tree so that they can be displayed in a nice structured way. The ideas and implementation are still perfectly valid.