# Hash

The `Hash` operation computes the root hash of the entire trie. This root hash uniquely represents the current state of the trie. Any change, no matter how small, results in a completely different root hash. This property is vital for ensuring data integrity and is a fundamental aspect of Merkle trees.

#### 🪜 Steps to Compute the Root Hash:

1. **Fetch the Current Root:**\
   Start the hashing process from the current root of the trie.
2. **Leaf Node Hashing:**\
   If the current node is a leaf node:
   * Serialize the node's key and value (RLP + Raw Data).
   * Hash the serialized data using a cryptographic hash function Keccak256.
3. **Branch Node Hashing:**
   * If the current node is a branch node:
     * Recursively compute the hash for each of its children.
     * Serialize the hashes of the child nodes along with any value stored in the branch node itself (RLP + Raw Data).
     * Hash the serialized data using a cryptographic hash function Keccak256.
4. **Extension Node Hashing:**
   * If the current node is an extension node:
     * Compute the hash for its child node.
     * Serialize the node's nibble sequence along with the child hash (RLP + Raw Data).
     * Hash the serialized data using a cryptographic hash function Keccak256.
5.

```
**HashNode Handling:**
```

```
* If you encounter a HashNode:
  * Fetch the actual node it references.
  * Proceed with computing the hash for the fetched node.
```

6\. **Return the Root Hash:**

* After hashing the root node (and recursively hashing its children), the resultant hash value represents the root hash of the trie.