# Header

## Overview

The header is an data structure that describes a block. It includes information about the block, the transactions contained in the block, the current state of the chain in which the block belongs to. 

## Structure

| Field            | Type                                                                                                                                     | Description                                           |
| ---------------- | ---------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------- |
| creatorPubKey    | String                                                                                                                                   | The public key of the block creator.                  |
| difficulty       | [HexNumber](https://ellcrys.gitbook.io/ellcrys/~/edit/drafts/-LPGzTZQXM_D8Pctq4-D/v/master/object-references/hex-value-types#hexnumber)  | The difficulty of the block.                          |
| totalDifficulty  | [HexNumber](https://ellcrys.gitbook.io/ellcrys/~/edit/drafts/-LPGzTZQXM_D8Pctq4-D/v/master/object-references/hex-value-types#hexnumber)  | The cumulative difficulty of all blocks in the chain. |
| nonce            | [HexNumber](https://ellcrys.gitbook.io/ellcrys/~/edit/drafts/-LPGzTZQXM_D8Pctq4-D/v/master/object-references/hex-value-types#hexnumber)  | The nonce discovered during PoW computation.          |
| number           | [HexNumber](https://ellcrys.gitbook.io/ellcrys/~/edit/drafts/-LPGzTZQXM_D8Pctq4-D/v/master/object-references/hex-value-types#hexnumber)  | The block's number.                                   |
| parentHash       | String                                                                                                                                   | The hash of the parent block.                         |
| stateRoot        | String                                                                                                                                   | The merkle hash of the state tree.                    |
| transactionsRoot | String                                                                                                                                   | The merkle root of transactions in the block.         |
| timestamp        | [HexNumber](https://ellcrys.gitbook.io/ellcrys/~/edit/drafts/-LPGzTZQXM_D8Pctq4-D/v/master/object-references/hex-value-types#hexnumber)  | The unix timestamp of when the block was created.     |
| extra            | \[32][HexByte](https://ellcrys.gitbook.io/ellcrys/~/edit/drafts/-LPGzTZQXM_D8Pctq4-D/v/master/object-references/hex-value-types#hexbyte) | Extra data for future use.                            |

#### Example

```javascript
{
    "creatorPubKey": "48YQpehoRDYsivCbnedrz19DfTvh345PwWAKGN3jdUjPNdG3Lte",
    "difficulty": "0x989680",
    "extra": "0x",
    "nonce": "0x61879fb427b56cef",
    "number": "0x2",
    "parentHash": "0x211df3aed05b45d620850f40c9b4eac006da7ee0f76a7fa99d5ac16a2c2ca42c",
    "stateRoot": "0xc222870b2ca3f71d30b8d06b8e3f633812a8c0473cecc38b6fcc12eb5cad89ec",
    "timestamp": "0x5bda0ad4",
    "totalDifficulty": "0x1312d00",
    "transactionsRoot": "0x0000000000000000000000000000000000000000000000000000000000000000"
}
```


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