The file system is basically a simple abstraction: store data in a tree structure. The broader topic is how the tree structure can be 'disrupted' by less struc

The file system is basically a simple abstraction: store data in a tree structure. The broader topic is how the tree structure can be 'disrupted' by less structured data organization and what are the territories where the tree structure (or at least a very strong (hierarchical?) structure) seems to be the right abstraction for most people. For example let's take written communication: A Word document, a non-fiction book, is a tree structure. A wiki, or the web of tweets is not. The web itself is not a tree (web directories did not work out) while some parts of it (some websites, some webpages) are tree structured.