There was a strict social hierarchy with the Tsar at the top with the landowning nobility.
The majority of the population were serfs and half of them were property of the landowners.
Serfs could be bought and sold, needed permission to marry and they could be beaten and conscripted.
The other half belonged to the state and lived in mirs (village communes) controlled by the village elders.
There were some skilled workers (urban artisans), manufacturers and merchants but there was only a tiny middle class.
Class was based on birth and social mobility was limited by law.
Bizarrely, serfs, urban workers and tradesmen paid taxes but nobles and the clergy didn’t.
The Russian Empire was incredibly diverse with about 55% of the population being Russian, 22% Ukrainian, 8% Polish and then there were other nationalities such as Jews, Finns and Germans.