Chapter 1:
I learned that you can import a new feature layer into ArcGIS Online instead of creating one from scratch. In your map you have options to add tables and layer, change the base map used, and create charts and legends that go along with your map. You can also use the ArcGIS database to search for other layers as well as searching from an atlas. Within this function, you can have the option of making them transparent, as well as changing the style of and symbols of the map. These maps you can then share with others within your organization, or publish to the Map so that anyone can access it publicly. You can create story maps (kind of like slide shows) that can include images, videos, and other media throughout your map.
Chapter 2:
ArcGIS Online has a very large selection of templates available, each are for different data, such as collecting and categorizing data of for things such as 3D scenes. Each WebGIS app is formed from 3 components, the baseman, the operational layers and th additional tools for that project. A living Atlas is an ESRI hosted collection of maps, apps and databases available to add in and use with your own applications and maps. Arcade allows you to use expressions to manipulate the data that you already have collected instead of needing to change the underlying data.
One potential application that this could be used with is to map all of the roads in the area and also map all of the major businesses in the area, this could give you a good idea of if the road ways are in the most effective layout.