Here we're using the Default Denoise settings but there are other useful settings:

• Volumes - used to denoise volume renderings (where the volume is rendered alone on transparent black)
• Alpha - used to denoise the alpha mask

You can also choose different modes:

• Frame - denoise a single frame
• Crossframe - denoise an animation of multiple frames (this requires multiple frames to be available to begin the denoise process instead of each frame immediately as it finishes)

Incremental renders can be any bucket order using Recovery and Denoise. Non-incremental must be horizontal or vertical bucket order when using Recovery and Denoise.