• by Gavin O'Malley , Staff Writer @mp_gavin, December 30, 2015

What is Facebook if not a single linear feed filled with all manner of personalized matter?

Well, challenging its existential limits, the social giant appears to be testing topic-based feeds in place of a single News Feed.

“Facebook is adding customizable interest-based feeds,” notes Jason Stein, a Brooklyn-based entrepreneur who first noticed the test this week.

In the pursuit of greater mobile engagement, Facebook is testing a number of new ways to present and arrange content. This latest effort is similar to Facebook’s Paper app, which automatically sorts posts into clearly defined sections like “Style,” Travel,” and Headlines.”

Facebook also recently rolled out Notify, a standalone app that encourages users to subscribe to push notifications from various content providers. No small side project, Notify launched with more than 70 big-name publishers, including Bloomberg, Comedy Central, CNN and The Weather Channel.

Just as with Twitter, Notify users are expected to select the stations that appeal to them to create their own content mix. The app also offers station suggestions, based on users’ Facebook profile information.

Add Facebook’s Instant Articles initiative -- plus the recent expansion of its Notifications system -- and it’s clear to see that the only constant for Facebook is change.