Para.3 4Twitter claims 100 million active users. 5And Nielsen estimates that social media sites and blogs reach 80%of all active U.S.Internet users. 6It's not just the volume of individual pieces of data,but the aggregation of that data that starts to really raise the hackles of privacy advocates.Para. 3 ④Twitter claims 100 million active users. ⑤And Nielsen estimates that social media sites and blogs reach 80% of all active U.S. Internet users. ⑥It's not just the volume of individual pieces of data, but the aggregation of that data that starts to really raise the hackles of privacy advocates