What does a YANG model define?

A YANG model defines a standardized, hierarchical data structure for configuration and operational data, independent of the underlying transport protocol. This allows network devices to expose their capabilities and data in a consistent, machine-readable format. While YANG models are commonly used with NETCONF and RESTCONF, the model itself is separate from the transport mechanism, enabling flexibility. The creation of transport protocols is a separate engineering task, not defined by YANG. User access to the CLI is a traditional interaction method, distinct from programmatic interfaces defined by YANG. Although often used with NETCONF/RESTCONF, YANG's data modeling is not limited to these specific transports; it defines the data, not the transport.