Networking is transportation of bits through space. A network should support connectivity of nodes (and components within) and ideally have low latency, high bandwidth, high reliability, and concurrent connections. The needs of the network should support the needs of the applications that users want to run.
In high performance computing a network might be an Infiniband fabric, and in a simple local network you might just have ethernet, or on cloud something like elastic fiber adapted (EFA on AWS). Often networks are optimized for specific hardware resources (e.g., Google TPU) with preference placed to a particular customer base or application need.
Converged Computing Authors. "Network." Converged Computing Community Space 29 Nov 2024, https://converged-computing.org/docs/network/ (accessed 29 Nov 24). [doi]