# Documentation

There are many specifications as well as tools that follow those specifications for documenting APIs. The 2 most common [API Description Languages](https://api-university.com/blog/what-are-api-description-languages) are [OpenAPI ](https://swagger.io/specification)(previously known as the Swagger Specifications) and [RAML ](https://raml.org/developers/raml-100-tutorial)(RESTful API Modeling Language). The OpenAPI specification created by [Swagger](https://swagger.io) is the most common and most popular among the API Description Languages. We will be using the OpenAPI specification in our application to document our RESTful API later in this book.

Both the OpenAPI and RAML official specifications and documentations are available online. Take some time to read through some of it to decide which would suit your documentation style.

{% embed url="<https://swagger.io/specification>" %}
<https://swagger.io/specification>
{% endembed %}

{% embed url="<https://github.com/raml-org/raml-spec/blob/master/versions/raml-10/raml-10.md>" %}
<https://github.com/raml-org/raml-spec/blob/master/versions/raml-10/raml-10.md>
{% endembed %}


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://book.restfulnode.com/part-2/chapter-3/9-documentation.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.