ArcGIS Server supports software development on the .NET Framework and the Java (programming language). ArcGIS Server services can be consumed by web browsers, mobile devices and desktop systems. ArcGIS Server supports interoperability standards such as OGC and W3C. Several service like mapping services, geocoding services, geodata management services, geoprocessing services, virtual globe services and network analysis services are available via a SOAP API.
ArcGIS Server is typically used by organizations that want to distribute their own GIS data. ArcWeb Services, another ESRI product, is typically used by organizations that want to use provided GIS data.
ArcGIS Server is part of a general trend in GIS development to abstract data delivery mechanisms from physical storage formats. In the services paradigm, services are consumed by applications through a specified interface.
Testing the performance of ArcGIS Server, performance reports, hints for optimization: AGS Performance Tool for ArcGIS Server Java Edition