> 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="https://3768097118-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbZbZJaVEcvTVbFKSbWIl%2Fuploads%2FXAchWGwolmT85L0iexqh%2FQuery%20Pipeline%20(16).png?alt=media&amp;token=eaf1aa4f-95e3-4eb1-ae81-a2e02372d5d4" 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.