ArcGIS Online provides a common platform to find, share, and organize geographic content and to build GIS applications. Through ArcGIS.com, the Web interface for ArcGIS Online, you can access maps, apps, and tools published by Esri and other GIS users, and share your own content with a broad community of users.
With ArcGIS Online, you can
Access free, high-quality and ready-to-use basemaps for your GIS projects.
Create and join groups to contribute your content and collaborate on specific projects.
Develop Web applications quickly with ArcGIS Web Mapping APIs and ready-to-use ArcGIS Online content.
Save time and money because you don't have to invest in additional infrastructure or staffing. ArcGIS Online is hosted by Esri and powered by ArcGIS Server and ArcGIS Data Appliance and new content is added and updated continually.
Contribute your geographic data content. Let Esri publish and host your authoritative content as part of a community basemap that GIS users can access freely through ArcGIS Online as a map services.