Edit Mesh > Crease Tool

You can crease edges and vertices on a polygon mesh using the Crease Tool ( Edit Mesh > Crease Tool). This lets you modify your polygonal meshes and obtain shapes that transition between hard and smooth, without unduly increasing the resolution of the base mesh.

You can also + -click on an object when you are in either edge or vertex selection mode to select the Crease Tool.

Edit Mesh > Crease Tool >

Mode

Select one of the following:

Absolute: The creasing for multiple edges and vertices is the same when the Absolute setting is turned on. That is, if you select more than one edge or vertex to crease and they have pre-existing creases, all of the selected components will have similar crease values when you are done. This is the default setting. The crease values can range between 0 and 7. A value of 7 indicates the component is fully creased.
Relative: The creasing for multiple edges and vertices is maintained relative to each other when the Relative setting is turned on. Use this setting when you want to maintain pre-existing creases on your mesh and you need to increase or decrease the amount of creasing overall.

Selection: When the Extend to creased components setting is turned on, the selection of creased edges is automatically extended to any creases that connect to the selection. This saves you the effort of having to select all of the creases separately. This option has no effect when creasing vertices.

NoteA heads-up display (HUD) appears in the viewport when using the Crease Tool. It displays the crease Mode, current crease value, and the maximum crease value possible for the current subdivision level on the mesh. When the Mode is set to Relative, the current crease value displayed in the HUD indicates the offset value relative to the current crease setting for those components.