Millennials' online communities aren't just social networks. They also take on the form of content and knowledge sharing through microblogging sites like Tumblr and video platforms like YouTube. Tumblr has 420 million users, for instance, and one billion YouTube videos are watching on mobile phones every day.
Like social networks, millennials have flocked to content sharing platforms that allow them to express their ideas and opinions with friends, family, and the world at large. They love to share, connect, comment, and express themselves – they just feel more comfortable doing it online. That's why so many new social websites have popped up as millennials matured.