Applications typically run on servers which are quite different from user workstations. Servers can be physical or virtual. Administrators need to know what hardware and software is on the application servers.
servers; physical; virtual; SAN; local drive; RAID; NIC; operating systems; Windows; Linux; UNIX; services; daemons; environment variables; accounts; shadow copies; reboot
The application you support almost certainly runs on a server. The exceptions to this would be a very limited application that is loaded directly onto a user’s workstation. Applications of this nature certainly aren’t available enterprise-wide and wouldn’t typically require the services of an Application Administrator.
The singular ...