Twitter has just announced that it hit the 200 million user milestone — that's active users on the service on a monthly basis. Twitter previously announced a high of 140 million active users back on its sixth birthday, so this is a pretty big milestone for one of the dominant players in social media (though it's still significantly trailing the one billion user Facebook juggernaut). This milestone caps a huge year for the microblogging service — its recent look back at 2012 showed Twitter playing a major role in a wide variety of world events, but it wasn't all good news. The recent spat with Instagram has dampened some of the positivity surrounding both companies, and its addition of photo filters felt like the service missed the point on what drove users to Instagram in the first place. This comes one day after Twitter's new partnership with Nielsen which saw the company announce that its users send more than one billion tweets every 2.5 days.