> For the complete documentation index, see [llms.txt](https://gl-docs.gitbook.io/zkpass/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gl-docs.gitbook.io/zkpass/getting-started/key-concepts.md).

# Key Concepts

The concepts of User Data, Data Verification Request (DVR), and zkPass Proof are central to understanding how zkPass works. The diagram below illustrates the relationship among the three:\ <br>

<figure><img src="/files/jwEyvHyzSqkz7TD1p4LZ" alt="" width="347"><figcaption></figcaption></figure>

The user data and the DVR, which contains the query, are inputs to the zkPass Service, which are needed to create the zkPass proof object.