In 2006, the Internet company AOL released a large excerpt from its web search query logs to the public. AOL did not identify users in the report, but personally identifiable information was present in many of the queries. This allowed some users to be identified by their search queries. Although AOL took down the file within a few days, it had already been widely copied and still remains available.
Overview
On August 4, 2006, AOL Research, headed by Abdur Chowdhury, released a compressed text file on one of its websites containing twenty million search queries for over 650,000 users over a three-month period; it was intended for research. AOL deleted the file on their site by August 7, but not before it had been copied and distributed on the Internet.
AOL did not identify users in the report; however, personally identifiable information was present in many of the queries. As the queries were attributed by AOL to particular user numerically identified accounts, an individual could be identified and matched to their account and search history. The New York Times was able to locate an individual from the released and anonymized search...