Twitter's (TWTR) iOS and Android apps have been updated to place much greater emphasis on the service's direct messaging (DM) feature - a DM tab has been added to the apps' main navigation bar - and to enable photo-sharing via DMs.
The update is aimed squarely at contending with the popularity of mobile messaging apps such as WhatsApp, Kik, Line, and Viber. Though centered around basic messaging services, the apps have added support for photo/video-sharing, 3rd-party games, and even payments, and in doing so represent a challenge to Facebook (FB) and Twitter's engagement rates.
WhatsApp alone had 350M+ monthly active users (MAUs) as of October, and Line has 300M+ registered users. Twitter had 231.7M MAUs at the end of Q3.