As part of the Open Archive Initiative (OAI) the Universities of Illinois & Michigan are developing technology to unlock materials held in the digital collections of various libraries and similar institutions. The schools are developing software necessary to search the databases of these collections for materials not generally indexed by ordinary/general purpose search engines. The schools are also developing an interface for searchers to access the material.

Materials not readily available via a search engine, infomration held in a database, or sites that for some other reason cannot be found without knowing (in advance) the web address for the site housing it are commonly referred to as the "hidden" or "invisible" web.

Examples of material in these databases hidden from most search engines include:

• Audio
• E-Books
• Images
• Movies
• Online Journals

Searchable via the University of Illinois' Cultural Heritage Repository, the collection currently includes materials from the following sources (among others):

• Online Archive of California
• Cornell University Rare Book & Manuscript Collection
• Harvard University Libraries
• University of Tennessee Special Collections
• University of Texas' Harry Ransom Humanities Center

Click here for more information on resources searchable via the OAI project.