The online media landscape is constantly evolving. Here are five trends to watch in 2015:

1. Mobile. Online consumers are shifting from desktop computers to mobile devices. This is disrupting the digital advertising market. Banner ads are more intrusive and less effective on smaller screens, challenging advertisers to adapt campaigns to suit the new medium. Mobile users are likelier to find their content using apps than browsers, which makes it easier for owners of the apps to track users across devices, and to serve targeted ads directly.

2. Social Media. Social media platforms have become more adept at exploiting their advantages as advertising media, and are attracting a growing share of advertising dollars. All users must log in when using a social media service, whether using a browser or a mobile app, providing information that permits powerful personalization of content. Many websites encourage users to log in using their existing Facebook or Twitter accounts, which increases the data flow. Native advertising is also seamless on social media, appearing as sponsored posts as users scroll down their timelines. Less intrusive ads are more effective ads. When ads appear as part of an endless scroll, it is less critical for advertisers to make sure their content appears “above the fold.”

3. Video. Video will become increasingly integrated in the online experience. The Facebook Auto-Play feature starts a video running when the user scrolls to it. The feature launched in late 2013 for user videos but rapidly rolled out so that advertisers could take advantage of it as well. This has proven to be a very powerful medium. To give one example, Apple’s holiday ad “The Song,” posted seven time the views on Facebook as on YouTube between its December 14 launch and Christmas Day. Not to be outdone, Twitter has just launched its own video feature.

4. YouTube Nation. The market for online content has hit that tipping point at which YouTubers have become real celebrities, with book and endorsement deals, television roles and personal appearances on top of significant advertising revenue. This has spawned an entire ecosystem of multichannel networks (MCNs) that intermediate between YouTube and the creators, providing them with production, ad sales and marketing support in exchange for a share of revenues. The feverish round of MCN investments and acquisitions over the past couple of years suggests that the smart money is looking for continued growth in this arena.

5. The Next Big Thing. YouTube has already redefined what we think of as entertainment content. Millennials are building intensely loyal followings by talking into webcams in their bedrooms. Vine, a platform on which users post six-second videos that play in loops, exploded this year. Top Viners have become genuine celebrities, with brand deals to match. Snapchat, which built its viewership on user-generated videos that self-destruct, is starting to monetize its audience using sponsored videos on its new Snapchat Discover feature. Snapchat is the current Next Big Thing. There will be others.

Just as the growth in online media has shaken up television business models, online media itself is continuing to evolve and mature rapidly. Challenging as it may be, it behooves media professionals of all stripes to keep abreast of developments in this new world.