# Bearer Authentication ## About Bearer Authentication Bearer authentication (also called token authentication) is a HTTP authentication scheme that involves security tokens called bearer tokens. Note that bearer authentication should only be used over HTTPS (SSL). For more information, [see here](https://swagger.io/docs/specification/authentication/bearer-authentication/). In the rest of this guide, we will use "API key" to refer to the bearer token used for authentication. ## Authentication Header Postman uses bearer authentication. In practice, this means that clients calling our API should include the API key in the `Authorization` header when making requests: ```http Authorization: Bearer ``` --- # 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://postman-v1.guides.gov.sg/email-api-guide/api-key-management/bearer-authentication.md?ask= ``` 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.