Sharpens the edges of selected mesh subobjects.

Button
Ribbon: Mesh tab
Mesh
panel
Add
CreaseNot available on the ribbon in
the current workspace
Menu: Modify
Mesh
Editing
CreaseNot available in menus
in the current workspace
Toolbar: Smooth
Mesh
You can sharpen, or crease, the edges of mesh objects. Creasing deforms mesh faces and edges that are adjacent to the selected subobject. Creases added to mesh that has no smoothness are not apparent until the mesh is smoothed.

You can also apply creases to mesh subobjects by changing the crease type and crease level in the Properties palette.