> For the complete documentation index, see [llms.txt](https://docs.blynk.io/en/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.blynk.io/en/concepts/device.md). # Device A device can be an MCU-based hardware (e.g. NodeMCU, Arduino, Raspberry Pi, etc), a finished physical product like a Smart Air Conditioner, or a virtual service that sends data to Blynk.Cloud using REST API. ## AuthToken Every device on the Blynk platform has an AuthToken – a unique identifier generated by Blynk.Cloud that is used to authenticate, validate, and connect devices to Blynk.Cloud. You can find it in the Device Info section of the required device: ![Authtoken](https://user-images.githubusercontent.com/72824404/120668495-300a0180-c497-11eb-8858-9dbf413d787f.png) AuthToken is usually not exposed to the end users due to security reasons (for the same reason you should not display it for public view anywhere). ## Template Inheritance Every device inherits a [Device Template](/en/concepts/device-template.md). Make sure you understand this concept before you start building something on Blynk platform. ## Ownership A Device always belongs to an Organization and usually has an owner. In most common cases, it's a user who activated the device. However, ownership can be changed by transferring the device to a different user or Organization. Owner of the device could be found under the device name: ![Ownership](https://user-images.githubusercontent.com/72824404/119472965-5fac6180-bd53-11eb-8178-84492a46bc76.png) Click on the owner name will open the user profile in case you have enough permissions to view it. Device owner is used mostly for the permissions to restrict the devices access within the organization. ## Access Access to a particular device can be limited based on the user role and a set of permissions. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.blynk.io/en/concepts/device.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. 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.