Twitter is rolling out an algorithmically generated timeline that will show tweets out of order.
Starting Wednesday, tweets that Twitter thinks people most want to see will appear at the top of the timeline beginning with the most recent first, a departure from the reverse-chronological format that has been fundamental to the real-time service since its founding.
Unlike Facebook, the timeline won't be entirely ranked by relevance.
The tweets will show up after users open the app or web service and occasionally while they are using it.
After those tweets are shown, users will again see their timelines in reverse chronological order.
The new timeline is essentially an expansion of the "while you were away" feature introduced a year ago.
The new timeline will be turned on by default in coming weeks on Android, iOS and the Web, but users can turn it off.