Esri's early experiences in testing ArcGIS Online left us with the realization that we didn't know what questions to ask or how to think about managing and leveraging a collection of online content. In fact, one of our late realizations was that ArcGIS Online is a content management system. On this page, we will explain building Web Maps relative to the ArcGIS Online system.
There is a name for every kind of thing that can be published at ArcGIS Online. An item is what each piece of content in ArcGIS Online is called generically. Items have documentation; you can add items to Web Maps, and Web Maps are a type of item. You can manage your items in the My Content section of ArcGIS Online.
Some items are based on ArcGIS Services, such as map and image services, and there are different types of each. However, to build Web Maps, you only need to know that map and image services are what you will build your Web Map from. In GIS, maps are created using layers that reference data in a database. In ArcGIS Online, Web Maps are created using layers that reference services on a web server. Thus, the terms layers and services are often casually interchanged.
An important best practice is to add map or image service items to your Web Map. You can also add content to Web Maps that are not items in ArcGIS Online, such as browsing to a web server that is running ArcGIS Server and directly accessing the content. Although it is possible to make a Web Map this way, the work you do will not be reusable, meaning it can not be copied and pasted into another Web Map.
By creating map and image service items first, they can be reused in many Web Maps, and the documentation you create for these items can be accessed from those Web Maps no matter who makes them. Map service items also have the capability of storing Pop-ups. Thus, a Pop-up can be authored once and used in many Web Maps via that content item. Plus if the owner of that content item improves the Pop-up, then all the Web Maps using it will get the improvement as soon as it's been saved.
ArcGIS Online Groups help you by allowing you to focus on a specific audience to share content items with. Thus, it's best to think about creating groups that are dedicated to a specific topic, purpose, and audience. The ArcGIS Online Help has topics for creating groups and others that explain the how to participate and what to expect in the role of administering and owning a group.
Groups are a collecting point for content of a certain kind of topic or purpose whether that's a long-term public inventory or archive of content or a private short-term project that only key team members are invited. As collecting points, groups act in two ways: first is to be where the group's owner releases content, and second is to be where the owner and members share content with each other. In either case the group's content can optionally be shared with everyone, i.e., the content is public.
Once you have saved a few Web Maps you will want to learn more about using the My Content section of your ArcGIS Online account. Here are some tips that we found useful to get started.
It is generally easier and more reliable to manage where you share your content using the My Contents user interface because it allows you to select everything that needs to be shared in a certain way and to then consistently set where that collection of content will be shared. Note that this is important because how you share a Web Map also dictates how the map service items used in the Web Map must be shared, i.e., if the Web Map is shared to the public (everyone), then so must the map service items.