Check out this other new ArcGIS Blog about sharing with members across organizations. I find that this blog is particularly helpful to Geonet users as scenario 1 is a great way to provide specific users (like me, Karate_KElly) who you are working with on the forums access to your items without making them public. Check out the blog and let us know what you think in the comments below.
Once upon a UC, David Hansen, COO at Geo Jobe stated, “ArcGIS Online is the largest global repository of geospatial information in the history of the species.” And although the amount of data in ArcGIS Online is not the point of this blog, as of May 21st, 2018 around 17 million items that exist in ArcGIS Online. That is 17 million layers, maps, scenes, apps and files that can be used for data collection, analysis, presentations and more. The items have a variety of sharing settings that enable the public or specific groups of users to access content. Twenty-three percent of ArcGIS Online content is public, meaning that anyone can access and find content that has been shared without requiring a username and password. Thirty-one percent of the items are shared with specific users through the group or organizational sharing setting.