cagraham writes "Following close on the heels of Instagram's advertising announcement last week, Tumblr has signed an agreement with analytics firm DataSift to provide info to advertisers on user behavior. According to Yahoo! CEO Marissa Mayer, who oversaw the recent $1.1 billion purchase of Tumblr, advertising on the site will become increasingly prevalent throughout 2014. DataSift will provide advertisers with info on the 5.5 billion interactions that occur on the site each day. This makes Tumblr the latest in a slew of recent tech companies to turn towards targeted ads in an attempt to generate revenue." Twitter is another customer of DataSift.