The core of Spotlight NEON consists of three APIs:

NEON Loyalty API. This is the day-to-day API used by most websites and other applications connecting to NEON. It’s mostly based around Members. Note that the Loyalty API only support Entities which have been installed (or published).
NEON Interact API. This is a lightweight API for calls directly from HTML and Javascript. It gives access to certain basic interactions such as a Member's public profile or to track a link or carry out basic tasks such as subscribing to a Newsletter, recording a click event etc.
NEON Config API. This is used for configuring and administrating the platform and the Entities. It does not contain any APIs for dealing with Members. It is normally accessed through the NEON Portal.