# Introduction

Open Standard API is an API specification inherited from [EIP6239](http://eips.ethereum.org/EIPS/eip-6239) with additional interfaces defined.

Open Standard API is the basis of `Contact Open Standard`. Developers can integrate the Relation Protocol by implementing`Open Standard API`.

It consists of two parts:

* EIP6239 Specification: It defines the construct of the contract. It is the foundation for implementing business interfaces.
* Business Interface Definition: It defines the business logic of social network activities.