The Money Button API is similar to other web services like GitHub and Twitter. In order to make full use of the API, you must create an "app" in your user settings. When creating a new app, you will be be able to pick a few properties, such as the name of your app, and you will also be given a few pre-generated values. Every user has a default app.
The values for an app are:
Once you have created an app, you will be able to use the api-client to interface with the REST API, webhooks to receive payment updates, and OAuth to authenticate users and get permission to perform actions on their behalf.