Sessions can either be solo or group based.
Group sessions are scheduled in advance while a solo session can be created and joined immediately (or scheduled a few minutes from now with a warm-up in slope mode).
Group sessions can be private amongst club/team members or group of ride buddies or marked public which any Xert user is welcome to join.
Some public group sessions are hosted by Xert and those can be lesson based (Academy 101, 201) or they are titled “breakthrough” sessions.
Academy sessions will have a mostly low intensity workout you ride while listening to a lesson/slideshow presented by @ManofSteele.
Breakthrough sessions will include a much tougher workout designed to achieve a breakthrough under encouragement by the Xert host and with group dynamics at play.
Each rider is suffering in tandem based on their own fitness signature and you’ll likely push yourself harder than you would your own.
A rider board displays relative efforts and any breakthroughs achieved during the session. Even if you don’t have a breakthrough it’s a different experience riding in a group with an option to chat if you’d like.
Group sessions are a bit sparse at the moment since it’s off-season for indoor riding.
There have been requests to record them so they can be run on-demand as a solo session but I’m not sure if/when that may happen.
If you haven’t tried the Session Player for solo indoor workouts here’s a thread discussing the benefits –
Solo sessions? - General - Xert Community Forum (xertonline.com)