# Authentication

To use the product, it is necessary to authenticate with an access token, using the authentication system known as OAuth2.

Unico's OAuth2 authentication system supports server-to-server interaction between a web application and Unico services.

For this scenario, you will need a service account, which is an impersonal account that belongs to your application and not to an individual user. Your application calls the Unico APIs on behalf of the service account, so users are not directly involved. This scenario is called “two-legged OAuth”, or “2LO”. Typically, an application uses a service account when the application calls the Unico APIs to work with its own data instead of the user's data.

{% hint style="warning" %}
This is step zero to start your implementation, so don't skip this stage.
{% endhint %}


---

# 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://devcenter.unico.io/trust-en/integrations/integration-by-client/authentication.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.