HathiTrust respects the privacy of all visitors and users of its services. Information about privacy in different areas of HathiTrust is given below.
Surveys and Assessments
Information and data obtained by HathiTrust in support of assessment of services, collections, resources, etc., or in support of research related to repository services, are considered confidential and will not be shared except in aggregations or with the express permission of participants, to protect privacy.
HathiTrust's access systems (e.g., the temporary bibliographic catalog, full text search, Collection Builder, and PageTurner) frequently track or "log" the actions performed by users of those systems. In some cases, specialized services or enhancements to system functionality require retaining the transaction logging. In other cases, data that can be tied to individuals will be kept intact only for a limited period of time. Its use will be restricted to trouble-shooting and problem resolution related to system functions and service transactions. It is HathiTrust's policy that no transaction logging containing personal information will be shared with third parties.
Information from transaction logs may be aggregated for reporting on types of use and use of materials. For this purpose, information regarding individual identities or the source of the transaction will be removed. In the case of logs kept for a limited period of time (i.e., where transaction logging is not retained for services or enhancements), the precise duration of the period needed for storing full transaction level logging will be determined on a case-by-case basis. When the information is no longer reasonably useful for problem resolution, the original transaction logging information will be destroyed, and backups and other stored forms of the data will not be retained.
HathiTrust uses Shibboleth  as a mechanism to allow individuals affiliated with partner institutions to authenticate into HathiTrust. More about Shibboleth, including privacy, is available on HathiTrust's Shibboleth implementation page .
Individuals not affiliated with partner institutions can authenticate to create permanent collections in HathiTrust's Collection Builder using a University of Michigan Friend Account . Friend Accounts require a valid email address. Information about privacy and security for information at the University of Michigan can be found at http://www.itcs.umich.edu/itpolicies/ . Users may choose a username to build collections in HathiTrust. If users choose to make collections public, the username is displayed on the public list of collections on the Collection Builder home page . No information is displayed if collections are made private.
If you choose, you can opt out of this tracking by using one of the following methods:
- Turn off cookies in the preferences setting in your browser
- Use the Google Analytics opt-out browser add-on http://tools.google.com/dlpage/gaoptout 
Personally identifiable information in works in the repository
It is HathiTrust's general policy, in consultation with depositing institutions, to remove access to works or portions of works when significant personally identifiable information is exposed that creates a cause for concern (e.g., Social Security Numbers of living individuals). Works where access is limited in this way will be indicated as Limited (search-only) in HathiTrust search interfaces, and the landing page for an item itself or relevant portions of the item will indicate that the item has been closed due to privacy concerns.