The elements of IT infrastructure are as follows
Computing Infrastructure refers to the hardware and software components -- such as servers, storage, a network and virtualization software -- that are needed to support the computing requirements and provides the hardware and services that other systems and services are built on.
Network infrastructure is the hardware and software resources of an entire network that enable network connectivity, communication, operations and management of an enterprise network.
Storage infrastructure is typically composed of end-network hardware, where tenant data is eventually stored, as well as virtual systems that help push data and files from a client to a vendor network, and vice versa, during data retrieval.
Security infrastructure is more like all the systems working together to mitigate risk to malicious activity from both external and internal sources.