Flickr is an online photo sharing and hosting site created in 2004 that was acquired by Yahoo! in 2005. It allows users to upload, tag, and share photos either publicly or within private groups. While free accounts have upload limits, pro accounts cost $25 per year for unlimited uploads and ad-free browsing. Flickr is popular among Mac and Linux users and its demographics skew towards ages 18-34. Users have privacy controls over who can view their photos and can delete them at any time. However, Yahoo!'s privacy policy allows them to collect user data through cookies and share information with advertisers and partners. Businesses use Flickr to advertise and promote their brand by posting photos that drive traffic to their website.