ArcGIS Server Components
GIS server
The GIS server hosts your GIS resources, such as maps, globes, and address locators, and exposes them as services to client applications.
is composed of two distinct parts:
the server object manager (SOM) and
server object containers (SOCs).
As the name implies, the SOM manages the services running on the server. When a client application requests the use of a particular service, it's the SOM that actually provides one for the client to use.