The cloud and mobile technology are having a profound affect on GIS. ArcGIS Online is Esri's first step into cloud-based GIS services. Pricing is subscription-based; a combination of annual fees and credits. ArcGIS Online is different. It has made publishing of both public and private data from different sources far easier. In many ways it is a big advancement, making ArcGIS services more affordable and accessible. Indeed cloud-based services like ArcGIS Online represent the future of GIS.
As the diagram below shows, ArcGIS Online provides a single access point for mobile and Web applications to access maps, map and feature layers, and GIS services.
ArcGIS Online