Some of the very best PIMs allow you to organize your data according to your needs. Usually that involves using tags or categories. And a great deal of discussion has gone into whether tagging or categorization is more effective for people who are tracking large amounts of information.
What is the difference? Tagging is like sewing little labels on your socks, categorizing is like picking the specific drawer to pick each type of sock in. I would suggest that the best overview document is Shirkey's document here. He very effectively details the strengths and weaknesses of both methods. I would also suggest Christian Ricci's discussion for very clean examples of solid uses of Taxonomies.
After reading Shirkey's notes you may be left with the idea that Tags are the "One True and Useful Way". To the extent that he talks about (i.e. the world of the web) that may be very true. But in the world of PIM the many weaknesses of Taxonomies become strengths for an individual user. The first person I found that seems to have firmly grasped that is Paul Chen here. And so what I am aiming for is the use of Taxonomies where the user finds it works for them and tags as necessary.
For now I want to talk about Taxonomies (I will expand on tags in another post). First are some definitions. A Taxonomy is a representation of concepts (called Taxa) that have distinct relationships.
For example a Taxonomy of the communities I track in my PIM would have Work, Church, Family, and Friends. Friends would have a distinct subset of "College Friends" and Family would have related subsets for each family grouping for my immediate family, my wife's family and my ex-wife's family (see graphic above).
A taxonomy encodes the relationships between the concepts. These include:
- is-a-type-of relationships like spaghetti is-a-type-of pasta.
- is-an-instance-of-a relationship like "my spaghetti dinner" is-an-instance-of-a "spaghetti dinner".
- is-part-of relationship like Rome is-a-part-of Italy.
- is-associated-with relationship like Spaghetti is-associated-with Italy.
As an example, a taxonomy could have the following levels and relationships Calendar->Jim, Janice, Boys, Church, Work with additional subgroupings of Church->Board of Trustees, Worship Committee. Any type of object could be associated with any level such as Work but only those objects that have an Aspect of LIT would show up in a calendar view or a schedule view. Only those objects with the aspect of LIS would show up in a map view.
Of course, as a user my preference would be for being able to create and manipulate taxonomies quickly as well as associate searches with Taxa for the ability to create flexible taxonomies.