# Sidetree

[DID:ION](https://github.com/decentralized-identity/ion) leverages the blockchain-agnostic [Sidetree](https://identity.foundation/sidetree/spec/) protocol to anchor tens of thousands of DID/DPKI (Decentralized Public Key Infrastructure) operations into one single on-chain Bitcoin transaction. These transactions are encoded so [DID:ION](https://github.com/decentralized-identity/ion) nodes can fetch, store, and replicate hash-associated DID operation batches via IPFS (InterPlanetary File System). [DID:ION](https://github.com/decentralized-identity/ion) nodes process operations in batches that independently arrive at the corrected DPKI state for system IDs, without the need for consensus mechanisms, blockchain, or sidechain. Nodes can work in parallel to fetch, process, and assemble DIDs, allowing nodes to run tens of thousands of operations per seconds. This allows Zion to create a robust decentralize identifier network that does not require trusted intermediaries, centralized authorities, or secondary consensus mechanisms.<br>

## Sidetree Network Topology

<figure><img src="https://1814701336-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FrUu2gjtmzovXOYo4awR6%2Fuploads%2FT4ArlAWPk25DmqVoNCCu%2F19.png?alt=media&#x26;token=16357c28-1972-44db-a803-161d21ed4131" alt=""><figcaption><p>Sidetree Network Topology</p></figcaption></figure>

**Bitcoin Ledger:** Global [anchoring ](https://identity.foundation/sidetree/spec/#anchoring-system)and linear sequencing system for DID operations

**Sidetree nodes:** Nodes that interact with the [anchoring system](https://identity.foundation/sidetree/spec/#anchoring-system) to anchor operations, as well as fetch and replicate CAS network data.

**Content Accessible Storage(CAS):** A IPFS Network that Sidetree nodes utilize to distribute and replicate DID operation files.