The ArcGIS server is an ESRI-developed distributed system which helps users put geographical information on web apps for the purpose of expanding the usefulness of maps and bolstering other knowledge bases. ArcGIS also allows you to upload GIS resources like maps and other tools that you might want to share with business associates, clients, or leads. To know more, Visit: http://softwareandapplicationservices.blogspot.com/2018/08/what-is-arcgis-server-and-who-uses-it.html