When talking about references to topics in general,a fellow researcher always preferred to talk in terms of Topic Maps. The other day, I had time to read about Topic Maps. The following brief description is taken from Wikipedia:

Topic maps are an ISO standard for the representation and interchange of knowledge, with an emphasis on the findability of information. The standard is formally known as ISO/IEC 13250:2003.

A topic map can represent information using topics (representing any concept, from people, countries, and organizations to software modules, individual files, and events), associations (which represent the relationships between them), and occurrences (which represent relationships between topics and information resources relevant to them). They are thus similar to semantic networks and both concept and mind maps in many respects. In loose usage all those concepts are often used synonymously, though only topic maps are standardized.

The interested reader might also read the following documents:

• The TAO of Topic Maps
• What are Topic Maps
• TopicMaps.org

When I finished reading the documents. I asked myself how it differs from tagging in respect to usage. Tagging is so simple for bookmarking and annotation of bookmarks by using terms that come into your mind. In this respect, tagging is a representation of our associative memory, and hence, it is highly individual. Adding an extra level of complexity like in Topic Maps, never occurred to me feasible in the sense that people will like to use it. They prefer simplicity. However, it is very easy to map tags into topic maps and topic maps have some interesting advantages as stated by Lars Marius Garshol in his weblog: multiple names, different topics with the same name, and relationships between topics. This features introduce a much more reliable level of structuring knowledge. Have a look at Fuzzy.com, for instance.