Privacy Policy

MovieLens is an experimental platform for studying recommender systems, interface design, and online community design and theory. GroupLens Research has created this privacy statement to demonstrate our firm commitment to privacy. The following discloses our information gathering and dissemination practices for this site.

Server Logging

To accomplish our research, we need to monitor how people use the MovieLens interfaces. This includes recording when each user logs in, what pages the user requests, what movies the user rates, what predictions the user is shown, and what kinds of searches each user runs, among others. We represent users anonymously as numeric identifiers whenever possible, so that researchers do not know the real identity of the users in the data they are studying. However, we must store a mapping from email addresses to anonymous identifiers for the purpose of authenticating users at login, and resolving account issues such as forgotten passwords.


When you use the MovieLens system, we administer one or more browser cookies. These help identify you and store your preferences. They are not shared with other sites and are not used for advertisements.

Data Collection

When you register to use MovieLens, we ask you to supply the following information: Your e-mail address (used as your login name) and a password. Using your e-mail address allows you to easily remember your MovieLens username and recover your password. We won't send you mail without your permission.

Once you are a registered member of MovieLens, we ask you to provide ratings data for movies and/or videos that you have seen. This ratings data is used by the MovieLens system to infer your "tastes" in movies and make recommendations to users with similar tastes.

Your ratings profile may be made visible to other users of the MovieLens site with all identifying information removed. If you consent to share your movie ratings, information about your ratings may be visible to other users of the MovieLens site, identified by a publicly visible username of your choosing.

To participate in our conversation features (including message boards and member profiles), you will have to create a publicly visible username. This username and other information of your choosing will be visible to other users. You may modify this additional information and review your privacy settings at any time by clicking "Your Account" when logged in to MovieLens.

We occasionally run contests, conduct surveys, and/or implement additional features for the purpose of our research. Participation in these "extras" may require us to ask for contact information (such as email address) or additional data. This privacy statement does not cover such additional activities. A specific privacy statement will be made clearly available for each activity not covered under this statement, and participation in such activities will be made optional.

User Contact

When you register to use MovieLens, we ask for your permission to send you occasional email updates. On limited occasions, we may send e-mail messages to you announcing new features, explaining changes to the system, or inviting you to participate in special opportunities. If at a later time you decide you do not wish to receive these emails you may indicate this by following the directions in the opt-out section below.

Third Parties

MovieLens does not release e-mail addresses or names to any third parties. We may share your demographic data (without your name or e-mail address attached) in research results. Furthermore, we may refer to the tastes of individual users (without your name or e-mail address attached) in research results. Aside from the above, information is held as confidential as is practical within our secured database.

Security Measures

Members of the GroupLens Research group are made aware of our privacy policy and practices by reviewing this statement upon joining the team. User data is password protected and access to the database is limited to members of the research group.


If at any time you choose to no longer receive emails from the MovieLens team, you may indicate this by sending an email to or (preferably) by clicking "Your Preferences" when logged in to MovieLens.

Due to the way in which we archive data, it is generally not possible for us to completely remove your personal data from our systems. However, if you have specific concerns, please feel free to contact us and we will see what we can do.

Last Reviewed

This privacy statement is reviewed as needed and was last reviewed June 6, 2005.