> ## Documentation Index
> Fetch the complete documentation index at: https://docs.towns.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Stream Checkpointing

Stream Checkpointing is how Towns Protocol ensures data integrity of a stream on a secure L2 blockchain. This guide provides an in-depth understanding of the process, focusing on the mini block headers, their structure, and their role in the Towns Protocol.

## Mini Block Headers

Mini block headers serve as a compact summary of a mini block's contents, providing essential information needed to verify the integrity and finality of transactions within the Towns Protocol.

### Components of a Mini Block Header

A mini block header is an event that encapsulates several critical pieces of information:

1. **Hash of Previous Mini Block Header**: This links mini blocks in a chain, ensuring continuity and traceability.
2. **Hashes of Events**: These are references to the events included in the current mini block, acting as a summary of the block's content.
3. **Snapshots (0-1)**: Optional snapshots may be included for additional context or state information. (see [Snapshotting](./snapshotting))
4. **Vote Proof**: Evidence of consensus from participating nodes, confirming the validity of the mini block's contents.
5. **Signature**: The entire event is signed by the elected leader node, adding an additional layer of security and authenticity.

### Storage and Distribution

* **Local Storage by Nodes**: Each node participating in the Towns Protocol stores the mini block headers locally. This storage plays a critical role in maintaining the network's integrity and redundancy.
* **Sent to Clients**: Mini block headers are also transmitted to clients, providing them with the necessary information to verify transaction finality and integrity.

## Finality and Verification

Understanding the finality of transactions within the Towns Protocol is crucial for maintaining trust in the system. The mini block header plays a central role in this process:

* **Transaction Finality**: If a client or node possesses a mini block header and observes a transaction on the Towns Chain with the same header hash, the transaction can be considered final.
* **Verification Process**: The interconnected nature of the mini block headers, along with the consensus proof and node signatures, allows for a robust verification process, ensuring the authenticity and integrity of the data within the Towns Protocol.