ArcGIS Services enable you to share your GIS resources across an enterprise and across the Web. GIS resources are the authoritative maps, globes, locators, geodatabases, and tools that you manage. You can share these resources by publishing them to ArcGIS Online or ArcGIS Server, where they are exposed via REST, SOAP, and OGC interfaces.
Consider using service applications if:
- Your application must be loosely coupled with its clients.
- Your application must be shared with or consumed by other external applications.
- Your application must expose functionality that will be consumed by applications over the Internet, an intranet, and on the local machine.