content: I write budgets for the IT department for the company I work for.  I can try to answer this from my recent adventures. Servers, physical computer hardware, virtual servers and the things that most people think about when they see a "server room" in a tv or movie show. The software that runs on those servers including licensing, patching, compatibility tables, everything that makes it work and do what is expected of it.  This includes the web server software, logging in software (Active Directory LDAP etc) and the security softwares used to keep it running and free of virus and bad guys. Networking.  Switches, routers, all the cabling in a five building campus for me, wireless access, etc. Phones, oh god the phone.  I am not a fan of telephone infrastructure as we have VoIP phones, analog phones, fax machines, inter-building paging and intercom systems, old copper wiring from the 70's, fiber cable some brand new and some from the '00s.  Some of these systems are going to be replaced which means that everyone who has a phone and phone number has an opinion on how that system should work and why are you IT guys not listening to my crazy ideas! (sorry ranted a bit). Datacenters.  We hired a guy to help design the rooms that the servers sit in, so that we could save on energy, cooling, HVAC etc.  The guy we hired eventually stayed on and became a member of the server team.  Our desktop guys change filters etc in the two datacenters we run. Desktops, laptops, computers, cell phones.  This is a whole team.  These guys test the software we use with the Operating systems available, put the plans together to upgrade, support office applications and out management softwares, make and implement builds for the high end users, replace parts that fail in everything but the servers, are the antivirus people, and also train people on how to use office, photoshop, powerpoints and software like that. Then you have people who write software, people who design web sites and web applications.  These guys are a whole separate group that are considered "production" while I am considered "Infrastructure" along with the building and fleet maintenance people. All of this is IT work.  A friend works in a hospital and works on just about everything that plugs into a wall. He fixed a refrigerator for storing drugs, and has to support the doctors and nurses personal cell phones.    The sort answer here is honestly... whatever they pay you to do.