Twitter had 100 million active users logging in at least once a month and 50 million active users every day. In an article published on January 6, 2012, Twitter was confirmed to be the biggest social media network in Japan, with Facebook following closely in second. comScore confirmed this, stating that Japan was the only country in the world where Twitter leads Facebook. On March 31, 2014, Twitter announced there were 255 million monthly active users (MAUs) and 198 million mobile MAUs. In 2013, there were over 100 million users actively using Twitter daily and about 500 million Tweets every day,
Twitter follow an account and who a user has chosen to follow is also public, though accounts can be changed to "protected" which limits this information (and all tweets) to approved followers. Twitter collects personally identifiable information about its users and shares it with third parties as specified in its privacy policy. The service also reserves the right to sell this information as an asset if the company changes hands. While Twitter displays no advertising, advertisers can target users based on their history of tweets and may quote tweets in ads directed specifically to the user. A security vulnerability was reported