Denoising as a technology can save enormous amounts of time considering progressive rendering. In general the AI uses certain learning algorithms in order to dissolve odd colored pixels in every area of the render shot. The image will get more smooth coloring and less deteriorated regions. Render denoise can be very helpful in creating animated cg videos, cutting the production time immensely.
Simlab Composer with the new update 10.16 has a new denoising feature added checkout the image bellow for reference.