> For the complete documentation index, see [llms.txt](https://docs.ckbull.app/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ckbull.app/guides-and-concepts/introduction.md).

# Introduction

In this section, you can find detailed information about the main concepts that revolve around **CKBull Signer API.**

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Please note that this platform is in its first version, and therefore new concepts could be introduced in future versions.
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The main concepts are:

* **Sign in requests:** Requests generated by the dApp meant to identify a user and retrieve its metadata.
* **Transaction requests:** Requests that contain a transaction proposal and are expected to be signed by an identified user.

Since the two concepts are related, we recommend following the order of the guide.