This is an easy read with lots of interesting detail on Photos and non-destructive editing. Worth your time, and from an excellent source.

From the bio at the end of the article:

Nik Bhatt, formerly Senior Director of Engineering at Apple, led the Aperture and iPhoto engineering teams for several years. Afterward, he led imaging teams for Apple’s photo applications, including the teams responsible for Core Image and Apple’s RAW Camera library. He is now the developer of RAW Power, an advanced photo editing app for Mac and iOS.

Read the article.