Key terms and concepts related to Ontology

Here is a list of terminology and concepts that are frequently referred to throughout the documentation. This list can also be used a reference or starting point for users who are getting started with the Ontology framework.

Certain related terminology and concepts have been grouped together for ease of understanding and access.

All the term and concept definitions mentioned in this glossary are limited within the scope of Ontology.


A ledger-based network of nodes that function based on consensus and trust. All the functionality and applications work based on the implementation of the aforementioned characteristics which have been brought about using complex algorithms and cryptography.


A node is an instance or the most basic element of a node-based P2P network. The same definition applies to blockchain based networks which are P2P in nature, generally speaking.

In the context of the Ontology framework, a node is a functioning deployment of the official Go-based implementation of the Ontology core.


A block is a ledger unit where transaction records are registered with the corresponding transaction hashes with all the data being open and transparent for all the nodes to be accessed and synchronized with. Blocks can be referred to using their height in the chain. A collection of time synchronized and linked blocks essentially forms the blockchain.

Ontology blockchain offers fast blockchain generation rates with a new block being generated about every 6 seconds.


In the traditional sense, we understand transactions to be transmission or transfer of financial assets and goods. But in terms of blockchain, any transfer of data or message passing between two nodes of a network or the blockchain is considered a transaction. Each transaction has a transaction hash which can be used to find out details regarding the particular transaction.


ONT and ONG are Ontology chain's native tokens.


ONT is a cryptocurrency token that has gained popularity in the digital currency market. It can be used for general exchange purpose within applications that support it. Feel free to explore the dApps in ONTO. It can be exchanged for other digital currencies, e.g. Bitcoin or Ethereum, or fiat, e.g. USD, over exchange platforms that accept ONT, such as Binance and Huobi.

Characteristics of ONT:

  1. Can be used as a governance token on the Ontology chain for staking.

  2. Indivisible. i.e., the smallest unit of the token is limited to unity.

Token decimal:

Originally ONT was designed to have 0 decimal. After the upgrade at the block height of 13920000, it's updated to 9 decimals.


ONG is a cryptocurrency much like ONT.

Characteristics of ONG:

  1. ONG serves as the gas to perform operations on the Ontology blockchain. Each on-chain action, or a transaction consumes a small amount of gas fee.

  2. Divisible in nature. Smallest unit of ONG can be as small as 0.000000001 (precise to 9 decimal places)

Token decimal:

Originally ONG was designed to have 9 decimals. After the upgrade at the block height of 13920000, it's updated to 18 decimals.

Smart Contracts

Smart contracts are the fundamental units of logic as far their usage within the blockchain ecosystem is concerned. Smart contracts implement functionality by releasing assets on single, or multiple chains based on the business logic and architecture, when certain fixed and acknowledged contractual clauses are fulfilled, or fail to fulfill. Hence, smart contracts can be used to program complex logic and functionality without any constraints in terms of industry.

Smart Contract Development


The Neo virtual machine is the engine that processes and runs the AVM byte code generated upon compiling Ontology smart contracts. Currently NeoVM supports contracts written using Python and C#. Feel free to check out Ontology's online IDE SmartX (access using Google Chrome).

Web Assembly Framework - WASM

Just like NeoVM, the Webassembly framework has the capability of processing portable binary code. Applications can be developed using the Ontology framework and then compiled to optimized binary code which can then be processed by the Webassembly engine. The WASM framework currently supports Rust and C++.

WASM Contract

Digital Wallet

A wallet that allows the user to store and utilize digital currency. Ontology currently has three digital wallets available for usage, Cyano, a chrome plugin wallet, ONTO, which is available in the form of a mobile application, and OWallet, which is a desktop wallet.

dApp - Decentralized Application

A decentralized application implements features and the back end mechanism of a distributed system or network to achieve its business logic. Ontology provides the required framework and SDKs that facilitate dApp development. Follow the link below for a brief introduction to dApps.


Ontology Bridge supports the exchange between OEP-4 and ORC-20 tokens, and ONG transfer between Ontology addresses (a-) and Etheruem addresses (0x-). In the future, it will support NFT transfers.

Here's a detailed tutorial.


The Explorer is Ontology's trust verifier. Block, transaction and contract related information can be looked up conveniently using the corresponding identifiers such as the transaction hash, block height, contract hash, etc.

OEP - Ontology Enhancement Proposals

OEPs define new standards for tokens and token protocols based on the Ontology framework and the native tokens ONT and ONG. Please follow the following link for details on the currently existing OEP token protocols.

Token Protocols


An SDK is a collection of tools packaged together for easy access to developers. Ontology provides SDKs in all major languages to support dApp development and the developer community. Follow the link below to refer to the list of SDKs made available by Ontology.



A blanket term referring to the APIs provided by Ontology.

Restful API

The Restful API is primarily useful for fetching on-chain data by sending individual requests to obtain individual responses. The Restful API uses HTTP requests and responses to communicate data.


The Remote Procedure Call (RPC) API has been implemented based on the JSON-RPC protocol. RPC uses HTTP requests and responses to communicate data.

Websocket API

The Websocket API has been implemented based on the websocket protocol, which establishes a bi-directional link between the node and the chain that allows free flow of data.

Using the dAPI


In the context of a distributed network an entity could be an individual, institutions that verify trust based claims, government bodies, etc. with no limitations. Ontology's ONT ID and DDXF protocol involve entities that perform various functions to verify identity and exchange resources in a credibility and trust based network.


A digital identity that is assigned to entities in the Ontology network in order to serve as a digital identifier.



An abbreviation of Distributed Data Exchange Framework designed by Ontology that allows tokenization and exchange of data and claims via a marketplace. Click here for more details.



In the context of DDXF, a resource is anything that is available on the marketplace. A resource can be physical in nature such as articles of value, or a digital copy of creative production, or even processing power or storage from a cloud platform. Activities of exchange and transfer can be carried out on these resources using the exchange system in place.


A claim is a verifiable credential or ownership related assertion that holds value under specific circumstances in a trust network and can be used to represent information such as personal data, digital signatures, attributes and ownership status linked with physical objects, etc.

Trust Network

A decentralized network that involves entities that use the verifiable credentials and a trust mechanism to carry out transactions that can involve digital tokens or other tokenized assets.

Verifiable Credentials


An arbitrary number used in cryptographic communication. The number can only be used once.

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