Internal vs. External API Security: What to Know
Every API falls into one of two categories: Internal or external.
External APIs are APIs that developers use to integrate their applications with a third-party resource, such as a public cloud service or a SaaS application. This type of API is probably what you think of first and foremost when you think about APIs.
However, there are also internal APIs. These are the APIs that handle communication between the constituent parts of an application.