The battle of the social media networks is set to intensify in the coming weeks after Instagram became the latest app to offer a private messaging service for its users.Last month, Twitter enabled users to send a private message longer than the previously 140-character limit, but now the Facebook-owned app has decided to allow people to share pictures privately with another person, or as part of a group without the image going on their public profile.Currently, Facebook and WhatsApp are the most...
