What is PSurface used for?

Sorry if this is very trivial question but I can’t seem to find any documentation for this.

http://processing.github.io/processing-javadocs/core/processing/core/PSurfaceNone.html

The above link is what I found but the use of it is still unclear .

Maybe this thread will help: https://forum.processing.org/two/discussion/16262/sorry-where-can-i-find-documentation-about-psurface-or-surface-solved

@Mesalcode I found the link from this post but not very descriptive of its uses.