# Introduction
Welcome to the reference for Zuora Revenue REST API!
REST is a web-service protocol that lends itself to rapid development by
using everyday HTTP and JSON technology. Zuora Revenue provides various REST
APIs for data integration. Use these REST APIs to authenticate and integrate
data from the source ERP systems with Zuora Revenue.
All Zuora Revenue REST APIs are secured by using HTTPS. The authentication scheme is token-based authentication,
which means an authenticated user must generate a token and then use it for all subsequent APIs until the token expires.
This reference provides detailed descriptions about functions, requests, and responses of each REST API.
Zuora Revenue REST APIs can be broadly classified into the following categories:
* Authentication
* Inbound
* Outbound

**Remember:**
* The API service must be enabled for your tenant in the first place. Otherwise, the 405 error will be returned for every API request you submitted. To enable the API service, contact Zuora Revenue Support.
* Both the inbound and outbound operations require an authentication token to perform integration.
You can obtain the token by using the Authentication operation.
* You can find the Revenue object model on <a href="https://docs.zuora.com?resourceId=revenue-data-object-model" target="_blank">Zuora Revenue data object model</a>.