Tags in social tagging systems store meaning for the
taggers who have entered them, and other users often
share this understanding. The result of this, a folksonomy,
is typically used in several ways, including
information retrieval and clustering, serendipitous information
access, or visualization of folksonomic characteristics.
For these uses tags work pretty well; however,
the ambiguity of tags makes it difficult to use
them for more than searching and browsing. This
paper introduces examples of current programmatic
support in the form of mashups and highlights its
shortcomings. It identifies several types of tags based
on their structure and language, and discusses how
these types support programmatic uses. The main
part is the presentation of the ActiveTags system, a
browser extension with supporting server infrastructure.
Using it the same community process that creates
a folksonomy can be used to enhance tags with
programmatic meaning. Users are enabled to create
reliable mashups based on tags. Effectively, this leads
to customized views of Web pages with tagged content.
ActiveTags naturally increases the usability of
social tagging systems and further extends the notion
of user-generated content.