.Net Standard multi-targeting explainer
Ok, technically multi-targeting is a feature of MSBuild, not .Net Standard. In fact you don't even need .Net Standard to be one of your targets, though it's a popular choice. Confused? Want to know more? I have the video for you!
For more info check out the Merge Conflict podcast episode that inspired me
http://www.mergeconflict.fm/85
as well as Oren Novotny's in depth blog post
https://oren.codes/2017/01/04/multi-targeting-the-world-a-single-project-to-rule-them-all/