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ReturnValues Ethereum word cards

By Seungwon Go, CEO & Founder at ReturnValues (

As the premier Blockchain expertise company, ReturnValues distributes own manufactured Ethereum word cards to contribute the right ecosystem for the Blockchain..


A Blockchain platform borned in 2013 by Vitalik Buterin. Unlike Bitcoin, it aims to develop a platform for developing general-purpose service based on blockchain. It supports own full Turing language, called Solidity, which allows you to write programs like Smart Contract. It has high freedom and efficiency.

Smart Contract

The concept first proposed by Nick Szabo in 1994. It means signing and executing financial transactions, etc. through a digital contract, not a real contract. It is a program that writes contract terms in computer code and automatically executes coding contents when conditions are satisfied.


(Decenteralized application) This is a smart contract-based application service in the blockchain. Using the generated contract address and ABI, you can create smart contracts through a variety of libraries, such as Web3.js, and perform functions within the contracts.


A concept derived from the Turing Machine, invented by mathematician Alan Turing, that is a virtual machine that can solve all operations if it has infinite memory and time. Ethereum has enabled us to perform more complex functions than Bitcoin by using language with a complete Turing.

the DAO

(Decentralized Autonomic Organization) It means a decentralized autonomous organization. It is an organization with a governance system in which anonymous people participate freely around the world to jointly propose and autonomously decide projects.


A unit of cryptocurrency that is commonly used on the Ethereum network. This is marked ETH, and 1 Ether can be divided up to 18 decimal places and the smallest unit of Ether is called Wei. 10Wei¹⁸ will be 1 Ether. The maximum amount of issue is not currently set.


In order to process and validate transactions, you must use resources on the Ethereum network.
A unit of fees paid in return. The fee is awarded to the block creator as a reward and is also a device to prevent process such as a loop within the Smart Contract.


A structure that maps and stores a set of information by address. The required information is managed in the form of a Merkle Patricia trie and can be validated using the values contained in the block header. Depending on the address, nonce, balance, storageRoot and codeHash are managed as state.


This refers to the structure of the data to be sent to a different address in Ethereum. You can create or invoke a smart contract in transactions, and you can transfer the ether. The transaction must be signed by the sender with its own private key. Fees will be paid in the form of gas.


Structure used when a contract is executed and another contract is called. Messages are virtual structures that exist in the execution environment, without having to be stored. The gas consumed in the message execution affects the gas consumption of the transaction in which the message was invoked.


External Owned Accounts. This has no internal code, and you must sign it using the account’s private key to send the transaction. At the same time as you send transactions to another EOA or CA, you can send the Ether, distribute or invoke the contract.


Contract Accounts, which means the account for smart contracts, is created after creating contracts and distribute them to the network. Execute internal code via message from EOA, or CA. It is code-controlled and can store code, but it can not send messages directly to EOA.


When you generate a transaction, you need to sign with a private key to prove that you sent it, which is the asymmetric cryptography used in this process. The public key obtained through this algorithm validates the transaction and generates the ethereum account address.


Address value of the Ethereum account. The public key obtained by the ECDSA algorithm from the 32byte private key is hashed by the keccak256. And last 20bytes of the 32 bytes result value is used as the address of the account. There are two types of it: EOAs used by people and CAs used as contracts.


This is an Ethereum client program developed by the Ethereum Foundation using GO language. It is the most widely used client program and you can run the Ethereum node with the CLI. With Geth, Ethereum’s block chain data can be kept up-to-date, mined, and transactions can be sent and verified.


Contract-oriented programming language with object-oriented characteristics, which is used to create Smart Contract in Ethereum. This is designed for EVM, the Ethereum virtual machine, and can then be run on the Ethereum platform after compiling a contract code written in this language.


(Ethereum Virtual Machine) It’s a stack-based Turing complete virtual machine. You can access the data in the transaction, the data in the block header, and so on, and return results. The gas is consumed according to the specified rules of the code being executed.


(Application Binary Interface) Interface used to interact with smart contracts. Used both when approaching or interacting with a contract from outside the blockchain. The ABI for a contract is generated when that contract is compiled.


(Operation code) A machine language for operations that are transformed to enable the execution of smart contracts in EVM. Each time this code is executed, the program counter is incremented from 0 and the operation is repeated. GAS is consumed whenever these operations are performed.


This is a directed acyclic graph with no directional rotation. In the ethereum, approximately 2GB of files consist of seed hash are used to gain cache area when mining. The Full dataset of DAG will completely be changed at the time of 30,000(epoch) blocks created and create a new file.


The Proof of Work in Ethereum, which makes GPU computations more efficient by using DAG files, which are two-dimensional array data in mining. Unlike Bitcoin’s PoW, it is designed to prevent the use of memory to be mined using a mining machine, thus preventing the centralization of mining.


A protocol for invoking smart contracts from outside. Outside of the Smart contract, smart contract must be invoked in a defined format, and the Web3 library allows you to easily develop JSON structures without having to deal with them directly. Typically, JavaScript and Python libraries are used.


Client developed by Parity enterprise in the Rust language. Next to geth, the goal is to provide a lightweight, fast and highly available Ethereum client to miners, service providers, exchanges, and more. There are parts that have been implemented in a different way from geth.

Bootstrap Node

In order to find specific node in the Ethereum network, distributed environment is time-consuming. This is a node to solve this problem, and it has been storing a list of connected nodes for a period of time, so it can connect to the bootstrap node first when a node reconnects to the network.


The act of creating a block in Ethereum and getting compensation. It is like the PoW method that uses computing power like bit coin mining. Ethereum is designed to mine blocks through memory operations using DAG files to prevent exploitation of mining by the use of ASIC miner.

Merkle Patricia Trie

A structure used to manage data in the Ethereum. Each time a block is created, the modifications are made, and the the same part as before are not changed to save space. Information such as state, transaction, and receipt is managed by this structure and included in the block header.

Bloom Filter

A probabilistic data structure used to examine whether an element belongs to a set. It is called a probabilistic data structure because it determines whether an element belongs to a group or not. In Ethereum, it is used to validate and speed up block generation.


GasLimit is a concept that exists in both transactional and block headers. In a transaction, this refers to the maximum amount of gas that can be paid, and if the gas consumption exceeds GasLimit, the transaction fails. It means the maximum amount of gas can be consumed in the transaction.

Uncle Block

The word refers to a block that is not connected to the main chain due to the low difficulty value of the branching block in the Ethereum network. When an Uncle Block is included in the chain, the block miner receives an additional 3% and the Uncle Block miner receives an additional 93% reward.


It is a record of the execution result of the transaction that occurred in the ethereum network. It is a structure that contains contents such as status information after transaction processing, and the hash of the top node made of Merkle patricia trie structure is stored in the block header.

GHOST protocol

(GREEDY Heaviest Object subTree) An algorithm that rewards Uncle Blocks, selecting the chain with the largest difficulty weight when the chain is split. The shorter the block generation cycle, the more likely the chain will diverge.


Encoding package implemented to encode nested binary arrays within the Ethereum. This encoding scheme is used globally in the Ethereum, including the state of the block header and messages on the communication protocol, and the process is simple and maintains byte-level consistency.


A value that stochastically adjusts the period in which a block is created. It is adjusted to the value calculated from the difficulty of the previous block and the creation time. In this way, the block is adjusted to be generated every 15 seconds.


This is a hash value that proves that the operation has been sufficiently performed during mining. It changes the Nonce and derives MixHash in combination with the randomly extracted value from the DAG, compares it with the target hash range, and judges whether or not the mining is successful.


This is information that exists in the block header and transaction, respectively. In the block header, this value proves that the operation has been sufficiently performed with MixHash.This is the same number of times the transaction occurred at that address.


A block that has just been created can be considered to be included in a chain after a certain period of time and is called Finality. In PoW, there is a possibility that a chain that is more suitable than the current chain exists, so that Finality can be guaranteed stochastically.


Scalability is a concept that describes how many transactions can be handled in a short time. The disadvantage is that it takes a certain amount of time for the transaction to be processed because the nodes in the network need to share and verify information.


This means that a single database is split into a number of processes. This refers to a technology that divides, validates, and periodically reassembles the main chain to address this problem, as the data in a block will grow over time and performance will inevitably deteriorate.


A proposed solution to address the Scalability of Ethereum. A child chain is placed in the root chain, and only the minimum amount of data required to verify the child chain is stored in the rootchain. It improves performance by distributing tasks from one chain to several chains.


It is a project to convert the consensus algorithms from PoW to PoS. There is a Casper FFG that maintains the PoW and applies the PoS for a certain number of blocks, gradually changing the algorithm, and the Casper CBC project aimed at a complete PoS.

Zero Knowledge Proof

In cryptography, when someone tries to prove True to the other, it is a Interaction procedure that does not expose anything except True or False. In Ethereum, this can be useful for boosting performance if you apply it to the information that put in the block.

Raiden Network

It refers to the ability to process remittance directly from outside the chain, rather than being processed after a mining transaction using the state channel of the Ethereum network. Because it is P2P remittance method, it is remarkably fast and is characterized by low gas fee.


As a distributed messaging service, it provides an easy, secure, and efficient means of communication between dApps. Based on Ethereum’s P2P network, there is no central server, and both end-to-end connections and messages are encrypted, making it impossible to trace and browse.


P2P file sharing system based on an incentive system as a decentralized storage service. The file is stored in a distributed environment, and the Ethereum chain is used to write the index. Synchronized to swarm nodes with the same network ID, it can protected from DDoS attack and maintain high availability.


(InterPlanetary File System) A distributed file system. It is created to connect all computer devices by the same file system, using hypermedia protocols that are handled as files and IDs. It is very similar to Swarm, and because Swarm is currently in research, it is being used in place of Swarm.


This is a wallet program with key management function. It is one of the most widely used wallets. It is an extension application that allows you to manage Ether- and Ethereum-based tokens, deposit and send money, and send transactions from a Web browser without installing the Ethereum’s nodes.


As Ethereum’s block navigator, it allows you to search and browse the data in the ethereum chain on the Web. It provides charts of block inquiry, transaction processing status, supply of ethereum, and mining hash rate. In addition, it offers a variety of options including detailed views of contracts and APIs.


(Enterprise Ethereum Alliance) It is the world’s largest blockchain consortium created to develop, collaborate and partner with Ethereum-based enterprise blockchain technology. It is active in researches and seminars, provides open source for companies and has more than 300 companies including MS & intel.


(Ethereum Improvement Proposal) It is a proposed improvement to define Ethereum’s core, client API and smart contract standard to improve the performance of Ethereum. There are three types of EIPs: Standard track, Informational, and Meta. Anyone can submit it if they are compliant with a given flow.


It is a proposal (Ethereum Request for Comment) that defines technical standard rules for the implementation of tokens in smart contracts. It has guidelines for interfaces to basic operations, including token transfer, making it easy to develop to interact with other contracts.


One of the proposals that defined the standard for token generation. Tokens that follow this rule have unique IDs per unit token so can not be replaced with each other. While other tokens are made for common currency purposes, ERC-721 tokens can have unique traits and can be traced to each token.

Mnemonic code

This is a way to create a Seed from an English word listed in order, usually 12 to 24 words. The Wallet used in Ethereum is a Hierarchical Deterministic Wallet and uses this code as a seed. Even if you lose your private key, you can easily recover your Wallet through these words.


It is a Wallet with Ethereum client Geth and is the standard of ethereum wallet and browser that can run dApp service. Unlike Geth, it provides a user-friendly interface based on the GUI. Also, since it is a wallet for the pool node, it can be used by synchronizing all previous block information.



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