This is just my own personal definition: Information Technology is the industry that relates to the management of data, communications / connectivity, and the technology infrastructure that supports it.
So, the big areas of IT infrastructure are computing power (servers and clients), storage, networking switches / routers, and of course the Internet backbone.
Other aspects of IT include but are not limited to Internet security, cloud computing, cloud services, Big Data, BYOD, backup and recovery, wireless networking, etc... but these are subsets of the original definition in the first paragraph.
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