in 2006. As of January 20, 2016, Reddit is now the 32nd highest ranking in the world and Digg is no longer a social bookmarking platform and has dropped out of the top 1000. Folksonomy A simple form of shared vocabularies does emerge in social bookmarking systems (folksonomy). Collaborative tagging exhibits a form of complex systems (or self-organizing) dynamics. Although there is no central controlled vocabulary to constrain the actions of individual users, the distributions of tags that describe different resources have been shown to converge over time to stable power law distributions. Once such stable distributions form, the correlations between different tags can be examined to construct simple folksonomy graphs, which can be efficiently partitioned to obtain a form of community or shared vocabularies. While such vocabularies suffer from some of the informality problems described below, they can be seen as emerging from the decentralized actions of many users, as a form of crowdsourcing. From the point of view of search data, there are drawbacks to such tag-based systems: no standard set of keywords (i.e., a folksonomy instead of a controlled vocabulary), no standard for the structure of such tags (e.g., singular vs. plural, capitalization), mistagging due to spelling errors, tags that can have more than one meaning, unclear tags due to synonym/antonym confusion, unorthodox and personalized tag schemata from some users, and no mechanism for users to indicate hierarchical relationships between tags (e.g., a site might be labeled as both cheese and cheddar, with no mechanism that might indicate that cheddar is a refinement or sub-class of cheeses). Uses For individual users, social bookmarking can be useful as a way to access a consolidated set of bookmarks from various computers, organize large numbers of bookmarks, and share bookmarks with contacts. Institutions including businesses, libraries, and universities have used social bookmarking as a way to increase information sharing among members. Social bookmarking has also been used to improve web search. Enterprise bookmarking Libraries Libraries have found social bookmarking to be useful as an easy way to provide lists of informative links to patrons. The University of Pennsylvania (UP) was one of the first library adopters with its PennTags. Education Social bookmarking tools are an emerging educational technology that has been drawing more of educators' attention over the last several years. This technology offers knowledge sharing solutions and a social platform for interactions and discussions. These tools enable users to