A free, wiki-style, online "reference about the Earth, its natural environments, and their interaction with society," the Encyclopedia of Earth [2] comprises a searchable collection of collaborative, peer-reviewed, plain-language articles by scholars, professionals, educators, and experts.

The EoE was started in October 2006 to fulfill a need for a central repository of accurate, credible information about the Earth that would "meet the needs of diverse user communities." Currently more than 3,500 articles are posted, with new articles being added every week. Text of the Encyclopedia is available for use by the public under the "Attribution-ShareAlike 2.5" Creative Commons license.