ArcGIS for Server provides you with a full range of GIS server capabilities that allow you to transform the maps, imagery, data and GIS tools that you commonly use in ArcGIS for Desktop into fast, reliable Web services that you can use anywhere. You can use these services to support a wide variety of mapping applications, either on the Web or your local network.
You can choose from Basic, Standard, or Advanced editions of ArcGIS for Server. Each provides an increasing level of functionality. For further information visit the Esri Inc website.
For developers there is support across a number of web technologies with the Web APIs: