The difference between a tree structure and a flat, «tagged» structure:
Most of us are used to organizing information in a tree structure. Think of the files on your computer or the bookmarks in your web browser, stored in a tree-like structure of folders. Storing information in such a rigurous structure requires a) some previous planning («What folders should I create to put my files in?») and b) for each information item (file or bookmark) to belong to only one category (folder).
For the type of computer usage up until recently, this was all fine for the average user, and tree-like structures prevailed. However, as all those of us who have taken a «data structures» course in university know, there’s several other ways to organize information, and one of them is «tags».
Organizing information using tags may seem similar to using folders at first. Example: Let’s imagine that I have bookmarks in my browser («favorites», for all you IE users 🙂 organized tree-like in two folders: ‘software’, and ‘news’. in the software folder, I have bookmarks to the websites of all the software I use, while in the news folder I have all the news websites I visit on a daily basis. Under ‘software’, I create two subfolders: ‘windows’ and ‘linux’. However, what about software that is platform-independent (i.e. there are versions for both windows and linux)? I could solve this by adding the same bookmark in both subfolders, or I could create a third subfolder for those cases, but both cases have disadvantages:
in the first case it requires double the effort to add and to maintain a bookmark that belongs to both categories, while in the second case a bookmark to a windows software could be either in the ‘windows’ or in the ‘platform_independent’ subfolder (the same for a linux software).
I would not be facing this dilemma if I used tags to organize my bookmarks instead. I would create the following four tags: ‘news’, ‘software’, ‘windows’ and ‘linux’. To the news bookmarks I would add the ‘news’ tag, while to the software bookmarks I would add the ‘software’ tag and either the ‘windows’ or the ‘linux’ or both the ‘windows’ and the ‘linux’ tag. This way, by selecting the ‘software’ tag, I would see all my software bookmarks, by selecting ‘software’ and ‘windows’ I would see all my windows software bookmarks, both windows-only and platform-independent!
Tagged information organization is starting to slowly appear in some applications, mostly web-based: Gmail, YouTube, del.icio.us and others.