Categorize includes some bookmarks that have an affiliate id associated with the extension. (These bookmarks are part of the predefined bookmarks and are not added to the user's profile if the user declines to load any predefined bookmarks.) When a user uses such bookmarks to purchase goods or to get services, the service providers providing the goods and services contribute a small cut of the revenue generated to the affiliate accounts linked to the bookmarks. This action does not change the cost of the transaction for the user. The user simply pays whatever s/he was going to pay anyway; however, the owner of the linked affiliate account gets a small commission for facilitating the transaction. For instance, the Amazon.com bookmark that comes with Categorize includes an affiliate id, and if you purchase a book from Amazon.com using that bookmark, Amazon will deposit some portion of the purchase price of the book in the affiliate account associated with the bookmark.
Affiliate links are common on the web and they do not lead to any breach of privacy as businesses do not share any personal information of customers using affiliate links with their affiliates. The affiliates simply get a commission and nothing more.
Even so, some people may have privacy concerns because of the inclusion of bookmarks with affiliate ids. To address such concerns Categorize fully discloses any bookmarks with affiliate ids. The user can simply choose to remove them or s/he can choose not to add any predefined bookmarks in the first place.