# What is Urbit OS? Urbit OS is a personal server operating system that runs on any Unix box as a self-contained virtual machine. It's sometimes described as an "operating function": the current state of your urbit is computed by running its history through one function, called [Nock](/nock/what-is-nock.md). It's simple to understand, easy to secure, and trivial to reproduce exactly. This section describes the two components of Urbit OS proper: the kernel, called "Arvo", and its standard distribution (the "`%base` desk") that contains other essential functionality. If you're looking for one detailed overview of Urbit OS, read [the 2016 whitepaper](https://media.urbit.org/whitepaper.pdf) and [this 2024 article](https://urbitsystems.tech/article/v01-i01/eight-years-after-the-whitepaper) on what's changed since the whitepaper's publication. For information on the Urbit runtime that interprets Nock and talks to the host machine, see the [runtime](/build-on-urbit/runtime.md) section. --- # 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://docs.urbit.org/urbit-os/what-is-urbit-os.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.