Smoothing polygons

You can smooth a mesh in Maya a number of different ways. Each has its own advantages and limitations, and it is important to think about which method best suits your needs.

Smoothing method	Advantages	Limitations	When to use?
Smooth a mesh by adding new polygons	Allows you to increase detail only in areas of the mesh that need it Uses the OpenSubdiv Catmull-Clark subdivision method by default.	Adds divisions to the mesh, increasing the polygon count	When the final model is complete and ready to be sent down the pipeline. When you absolutely require the versatility of working with the high-res mesh (i.e. working with features that require the real geometry).
Smooth Mesh Preview (Hotkeys: 1, 2, 3)	Best performance No additional geometry created Uses the OpenSubdiv Catmull-Clark by default.	Can’t be smoothed linearly Complicated mirror setup Cannot collide with particles	In most cases you will want to use a smooth mesh preview When you want to see the effects of a smooth operation When you want to make changes to a smooth mesh by modifying its less complicated un-smoothed counterpart
Subdiv Proxy	Allows for linear smoothing Provides 1-click mirror smoothing Allows you to see the effect of particle collisions Uses the OpenSubdiv Catmull-Clark subdivision method by default.	Increases the polygon count	When you need to perform a linear smooth When you want to see the effect of particle collision on your smoothed object, prior to smoothing If you want to perform a mirrored smooth (though this can be recreated in a smooth mesh preview with a few extra steps)
Smooth by averaging distance between vertices	Maintains the current poly count of an object	Less versatility since only existing vertices can be used.	When under a strict poly count restriction. When you want to massage an area with a lot of spikes or dips.
Subdivision Surface	Lets you increase detail only in areas of the mesh that need it Lets you affect the mesh in different levels of detail	Slowest performance No external pipeline support (without first converting to polygons)	When modeling objects that are not going to be rigged When modeling with the intention of converting to NURBS