# Request Headers

This page covers main HTTP request headers that are used in YouTrack REST API. HTTP headers basically describe the API request and the data it contains or expects to be returned.

| Header | Description |
| --- | --- |
| `Authorization` | This header provides the authorization data for the request. Here is an example of an `Authorization` header using a Bearer token:      ```CURL 'Authorization: Bearer perm:am9obi5kb2U=.UG9zdG1hbiBKb2huIERvZQ==.jJe0eYhhkV271j1lCpfknNYOEakNk7' ```     If you don't provide an `Authorization` header, YouTrack makes the request on behalf of the guest user account. If the guest account is banned, the request will return an error. For more details about the guest user, see [Managing Guest User](https://www.jetbrains.com.cn/en-us/help/youtrack/cloud/managing-guest-users.html).     For details about supported authorization methods, read [Log in to YouTrack](api-log-in-to-youtrack.html).     |
| `Accept` | This header defines in which format you expect the response body to be returned by the server. Provide this header for `GET` methods, or if you request entity attributes in the `fields` request parameter for any other method, then also provide this header. YouTrack supports JSON format for returned data. That is, use `'Accept: application/json'`. |
| `Content-Type` |    This header defines in which format you send request payload data to the server. Provide this header for `POST` and `PUT` methods. YouTrack supports JSON format for the request payload data. That is, use `'Content-Type: application/json'`.      > **Tip:** > For attachments, YouTrack also supports other types for the `Content-Type` header. See examples on the [Attach Files to an Issue](api-usecase-attach-files.html) page.    |