Check out the key features in Blender 2.90 - BlenderNation
Subdivision Surface Modifier — Blender Manual
Subdivision behaviour is different than in any other software causing compatibility issues - #15 by postrowski5 - User Feedback - Blender Developer Talk
Subdivision Surface Modifier — Blender Manual
Problem with Subdivision Surface Modifier : r/blenderhelp
Subdivision Surface Modifier — Blender Manual
Subdivision Surface in Edit-Mode - Blender Development Discussion - Blender Artists Community