Infrastructures today are constructed as a collection of building blocks stacked together to form the system as a whole. The individual blocks represent the different technical domains such as; campus and branch, data center networking, compute, security, wireless and cloud. Effectively automating environments with disparate systems will require interacting with multiple systems programmatically.
The programmatic interface that is exposed by devices in your infrastructure is called an API.
GraphQL is a newer type of approach to APIs that is gaining ground quickly. GraphQL is extremely flexible and highly efficient.