Promises/A+ is an open standard that aims to provide a sound and interoperable solution for JavaScript promises. A promise represents the eventual result of an asynchronous operation, and it offers a primary method called then for interacting with it. This method registers callbacks to receive the promise's eventual value or the reason why it cannot be fulfilled.

The Promises/A+ specification serves as a stable base for all conformant promise implementations, ensuring interoperability. The specification focuses on the behavior of the then method and does not cover the creation, fulfillment, or rejection of promises. The organization behind Promises/A+ occasionally revises the specification, but only with minor backward-compatible changes.

The core specification does not deal with how to create, fulfill, or reject promises, leaving those aspects to companion specifications. Overall, Promises/A+ is a trusted standard that improves the functionality and compatibility of JavaScript promises