Google Book Search is a tool from Google that searches the full text of books that Google scans, OCRs, an stores in its digital database. The service was formerly known as Google Print when it was introduced at the Frankfurt Book Fair in October 2004. When relevant to a user's keyword search, up to three results from the Google Book Search index are displayed above search results in the Google Web Search service (google.com). A user may also search just for books at the dedicated Google Book Search service. Clicking a result from Google Book Search opens an interface in which the user may view pages from the book as well as content-related advertisements and links to the publisher's website and booksellers. Through a variety of access limitations and security measures, some based on user-tracking, Google limits the number of viewable pages and attempts to prevent page printing and text copying of material under copyright.