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Ethereum history

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Ethereum was designed to enable programming and execution of complex smart contracts.



In order to integrate smart contracts into the blockchain, Ethereum introduced a special type of account - a contract account, and a specific way to store transaction history as account fields. A special piece of software, the Ethereum Virtual Machine, is charged with smart contracts execution, and the  fees needed for this execution prevents the system from clogging due to unreasonably lengthy computations.



<h2>Ethereum accounts and their states</h2>



Ethereum distinguishes two types of accounts, each having its own address:



<ul><li>Contract accounts (smart contracts) – controlled by the logic of their code, which is recorded on the blockchain at the contract account creation. In response to a transaction targeting them, contract accounts can send and receive ETH, trigger the execution of particular functions according to the data received, and even call other contracts. However, they don’t have private keys and cannot initiate transactions themselves. </li><li>Externally owned accounts (EOA) – controlled by the owner of its private keys. By digitally signing a transaction an EOA can send messages to another EOA (as a simple asset transfer), or to a contract accounts, triggering their execution </li></ul>



<ul><li></li></ul>



Each account, whether an externally owned or containing a smart contract, has its fields (an ether balance and a nonce for both types, plus code and storage for contract accounts), and the mapping between the Ethereum addresses and the accounts and their fields composes the world state, unique for any given point in time. The World state changes with every transaction block, which is why Ethereum can be viewed as a distributed transaction-based state machine.



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<h2>Ethereum Virtual Machine </h2>



The key element of Ethereum allowing smart contract execution is Ethereum Virtual Machine (EVM), which is working as its runtime environment. EVM is a program that executes bytecode (machine-language instructions), compiled from high-level languages, in which smart contracts are written.&nbsp;



Each node on the Ethereum network runs a local copy of the EVM to validate contract execution, while the Ethereum blockchain records the changing World state resulting from processing transactions and smart contracts. More precisely, the world state is stored in the cryptographic Modified Merkle Patricia Trie (variant of a Merkle Tree), which is itself stored in blocks headers. 



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Everything registered on a blockchain has to be duplicated and run by multiple nodes without compromising the integrity of the system. Hence the code running inside the EVM has no access to network, filesystem or other processes - that is why the EVM is sometimes referred to as a “sandbox”, which is an IT speak for a security mechanism separating running programs, usually in an effort to mitigate system or software failures. Such isolation allows to execute instructions and protects the network from a potential vulnerability resulting from a malicious program. Only if the execution is successful the real world state is updated. 



<h2>Solidity</h2>



Solidity - the Ethereum-specific high-level language created by Gavin Wood - is not the only high-level language used to code smart contracts, but it is by far the most dominant one.&nbsp;



Most of today’s programming languages are Turing-complete (theoretically capable of expressing all tasks accomplishable by computers), and so is Solidity, allowing the creation of specific programs that can implement any detail you fancy.&nbsp;



However, if the whole system worked as a Turing machine, some programs could take ages to be executed and the system would be clogged (this is the base logic beyond the Distributed Denial-of-service attacks and one of the reasons why programs have to be terminable). Also, a good-intended developer may wish to terminate the calculations at a point where they become economically non-profitable. 



<h2>ETH and gas</h2>



Ethereum solves this problem by requiring a fee called gas for every operation within a transaction, and by asking users to declare a gas limit (maximum amount of gas  they are willing to pay for this transaction). Every transaction specifies the gas price it is willing to pay in ETH for each unit of gas, allowing the market to decide the relationship between the price of ETH and the cost of computing operations (as measured in gas). It’s the combination of the two, total gas used multiplied by gas price paid, that results in the total fee paid by a transaction. 



Blocks that are mined on the Ethereum blockchain have a gas limit attached to them, so the amount of gas used by all transactions inside a block cannot exceed a certain amount.



The gas cost not only incentivizes miners to perform their duties, but also deters malicious nodes from executing DDoS attacks that would cost them a fortune, thus making the attack useless. The gas limit prevents nodes from running unreasonably lengthy programs, keeping only those that are economically worthwhile.

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Ethereum governance

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Ethereum tokens

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The blockchain aiming at “decentralizing everything”, Ethereum brings its benefits to numerous domains by enabling complex smart contracts and Dapps.



Diverse use cases and the absence of an easily customizable blockchain helped formulate a need for a multi-purpose blockchain, on which a wide array of applications could be built. The first to come with a solution was a Russian-Canadian developer Vitalik Buterin, who submitted the Ethereum concept to the crypto community in late 2013. After a successful crowdfunding in 2014 the platform went live by July 2015.



The major innovation of Ethereum that distinguished it from <a href="https://d.center/explore/bitcoin" class="ek-link">Bitcoin </a>was a wide range of possible smart contracts that could be coded on its blockchain. A smart contract is basically a computer program registered on a blockchain that is executed by the EVM (Ethereum Virtual Machine) when a transaction is sent to its address; the results of a program execution are themselves being stored on a blockchain. The DApps (decentralized applications) using these smart contracts enjoy all security and independence benefits of a blockchain: program execution is entrusted to a decentralized network instead of a single third party.



<h2>Ethereum consensus and fees</h2>



In order to incentivize Ethereum nodes to run smart contracts, fees are paid for every transaction. These fees are paid in a special unit called gas and depend on the amount of computations to be done. Gas can be bought with Ethereum native currency Ether (ETH), the price being decided by the market according to the supply/demand ratio.&nbsp;



Ethereum uses a <a href="https://d.center/explore/proof-of-work" class="ek-link">Proof-of-Work</a> consensus, like Bitcoin, although it has some specificities of its own: hashing function is Ethash and a block is added every 15 seconds. Ethers are generated as a miner’s reward for adding a block, however there’s no hard cap on their total emission. Current yearly network issuance is approximately 4.5%, and will be reduced with ETH 2.0



<h2>Ethereum tokens</h2>



Ethereum is also a very convenient platform for the creation of tokens - digital units circulating on a blockchain and representing a certain value assigned to them by their creator. Its ERC20 (fungible) and ERC721 (non-fungible) tokens have become the standards in the industry and are being used extensively.



<h2>DAO</h2>



Ethereum can be used to build Decentralized Autonomous Organizations (DAO). A DAO is an organization with governance defined by smart contracts registered on a blockchain. A DAO allows a group of persons to interact using an open source protocol with auto-executing qualities; this protocol and the associated smart contracts formalize the organisation’s operation rules. Once deployed, a DAO is independent from its creator and isn’t controlled by an entity, but rather by a consensus between its participants, according to its blockchain-registered code. The owners of tokens associated with a DAO are assigned voting rights and are often rewarded for their participation in the DAO’s governance.



The transparency and immutability of the blockchain make such organizations difficult to corrupt, proposing an alternative model to centralized organizations. There are lots of DAO in the DeFi (Decentralized Finance), the most famous being Maker DAO - a lending platform managing the dollar-pegged stablecoin DAI.



<h2>ETH 2.0 and Casper&nbsp;</h2>



Ethereum relying on a PoW consensus, it has its standard disadvantages: the blockchain is rather slow, costly and energy consuming. To overcome these drawbacks an important update has been planned since Ethereum conception: initially called Serenity and now mostly referred to as ETH 2.0, this update has been released in December 2020. It has been deployed on a parallel chain first, in order to conduct all the necessary tests before becoming the main Ethereum chain.



ETH 2.0 relies on a consensus called Casper, which is a version of the <a href="https://d.center/explore/proof-of-stake" class="ek-link">PoS </a>consensus: validator nodes [tooltip content=" escrow in a special wallet"] stake [/tooltip] a minimum amount of 32 ETH to be able to propose a block or to validate it. The new consensus would also improve the blockchain’s scalability, allowing a blocktime of just a couple of seconds.



ETH 2.0 will also affect the annual Ether emission rate, which will be significantly decreased, or even become negative.



<h2>Ethereum today</h2>



Ethereum is the most popular blockchain for DApps development, with over 5000 DApps built on it. It is a major blockchain for the Decentralized Finance, or DeFi, with an important new metrics - TVL (Total Value Locked), representing the collateral locked in different types of DeFi applications - exceeding $50 BN worth of crypotoassets.&nbsp;



ETH 2.0 is a major ambition for Vitalik Buterin. According to the Ethereum creator, the 4 major problems that need to be solved to push Ethereum to the next level are privacy, consensus safety, smart contract safety, and  scalability. Some would add a governance issue to the list, for its role in blockchain’s life is crucial.&nbsp;

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Cardano

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Tezos is a self-correcting platform for smart contracts and Dapps created in 2015 and officially launched in 2018. Its creators Arthur and Kathleen Breitman, as well as their team of developers, put a lot of thought into the actual cryptoasset governance methods and came up with a blockchain capable of upgrading itself via a built-in governance system. Tezos upgrades are carried out on-chain once the majority of its participants agree to them, without the need to fork or split into separate chains, making Tezos self-amending. 



Before their marriage in 2013, Arthur Breitman worked in France in mathematics and computer science; he moved to the US to focus on financial mathematics. Mrs. Breitman was an executive at a hedge fund and a distributed database technology firm.&nbsp; 



Tezos consensus 



Tezos consensus is a variant of DPoS called Liquid Proof of Stake - a stake in Tezos native coin XTZ is associated to a voting right that can be delegated to a non-fixed number of block creators without losing stake ownership. The consensus is called liquid, because people can easily switch between voting directly to delegate their voting rights to others. 



The probability to create a block is proportionate to the nodes’ stake, plus the stake delegated to him by others. Each block is then endorsed by 32 other block creators. The creator of a successfully added block receives a block reward and transaction fees, which are then shared between him and his delegators. Block endorsers also get a reward for each endorsed block. 



To incentivize honest behavior of block creators (called bakers), Tezos requires them to own 8 000 XTZ and put up a safety deposit of 512 XTZ per block, and the endorsers 64 XTZ per endorsement . The bakers who register a faulty or a double entry would lose their stake and be voted out by other stakeholders. 



The LPoS consensus allows Tezos to have a higher transaction throughput (30-40 transactions per second) comparing to the PoW-based blockchains. Furthermore, a second layer solution called Marigold is being developed to assure even better scalability.



Tezos governance 



Anyone can submit an update proposal in the form of code, which is then voted on-chain. If the update is agreed upon by the majority of nodes, it is implemented on a testnet. A confirmation vote follows the test period, and if succeeded, the update goes live on the mainnet. 



Only block creators (bakers) can participate in voting rounds, however other XTZ holders can delegate their coins to a specific baker, thus increasing his or hers voting power. A vote is considered successful if it is agreed upon by 80% of nodes, at a condition that a quorum of 80% is reached.



The advantage of Tezos governance is its decentralization: the power is distributed among all coin holders instead of more centralized groups of developers and miners proper to other blockchains. The automatization of the upgrades also makes the blockchain resilient and fast adapting to changes. Furthermore, protocol updates are encouraged and rewarded with the newly created XTZ, stimulating innovation.



The first successful backwards-incompatible Tezos upgrade was conducted in 2019, after 3 months of voting and testing. Dubbed Athens A, this upgrade reduces the minimum quantity of XTZ needed to be staked in order to become a block validator, thus decentralizing the network.&nbsp;



Tezos today 



The company developing Tezos and owning its intellectual rights is called Dynamic Ledger Solutions.&nbsp;



In 2017 the Breitmans also created Tezos Foundation, a Switzerland-based non-profit, which in a 2017 ICO raised a then-record amount of $232m. These proceedings, however, became a source of dispute among the Breitmans and a then-president of the Foundation, leading to the dismissal of the former.&nbsp; 



Tezos Foundation is financing research projects relative to Tezos, the most noticeable being led by Nomadic Labs, a Paris-based software company focused on Tezos since 2015. Tezos itself has been written in 0Caml, a reliable, but not very popular outside of France software language of INRIA, the French Digital Science and Technology Institute.&nbsp;&nbsp; 



Tezos is still far behind Ethereum in terms of DApps built on it, however it is getting more and more traction, French blockchain developers being particularly enthusiastic.&nbsp;



The cyber crimes department of the French Gendarmerie notably uses Tezos for tracking&nbsp; certain expenses.



Another sector in which Tezos is becoming increasingly popular is STO, numerous companies preferring Tezos to Ethereum, considering the first more secure.&nbsp; 



Staking Tezos is now available on numerous exchanges, such as Binance, Kraken, Coinbase.

Tezos

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Blockchain in use

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Blockchain and DLT types

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Keys and addresses

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Adress

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Blockchain is a recent invention. It is still in early stages of its development, and yet a burgeoning new blockchain-related industry is already emerging. Improving the technology, finding new use cases, developing the ecosystem… and of course looking to change the world are some of these new endeavors.



This section is dedicated to exploring different facets of the blockchain and bringing answers to an array of questions one might have - from “Why do we need it” to “How does it work” or “What is it used for”. The structure of Explore descending from general concepts to specific notions, you are welcome to choose your own path according to your interests and go down the rabbit hole. 



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<h2><a href="https://d.center/explore/blockchain-philosophy" class="ek-link">Blockchain philosophy</a></h2>



Why are crypto enthusiasts so enthusiastic? Blockchain is not a trivial technology, but the one that has a potential to change the very way our societies operate. Every organization and every community rely on trusted third parties, responsible for storing and managing data, with all the related risks . Replacing these trusted third parties with a decentralized data handling mechanism would eliminate much of the system’s deficiencies, and that’s exactly what blockchain does. 



<h2><a href="https://d.center/explore/bitcoin" class="ek-link">Bitcoin</a></h2>



The very first implementation of the blockchain, Bitcoin was created to solve the deficiencies of the monetary system and replace the so-called fiat money (dependent on Central Banks) with cryptocurrency, a completely independent alternative that runs on a decentralized peer-to-peer network.&nbsp; 



<h2><a href="https://d.center/explore/blockchain-fundamentals" class="ek-link">Blockchain fundamentals</a></h2>



A blockchain is a collection of technologies and methods that allow gathering data into a ledger, which is stored and updated by the network’s participants (which anyone can become). Data handling is its main role, although it also allows embedding more complex programs and running them in a decentralized way.&nbsp; 



<h2><a href="https://d.center/explore/blockchain-in-practice" class="ek-link">Blockchain in practice</a></h2>



Most blockchain encounters today are about cryptocurrencies - Bitcoin and many others that have appeared since. However the understanding of the technology becoming increasingly subtle, other blockchain real-world use cases appear, notably with the development of decentralized applications, or Dapps. A developed ecosystem makes these functionalities readily available and opens up previously restricted-access industries, such as finance.&nbsp;&nbsp; 



<h2><a href="https://d.center/explore/crypto-regulation" class="ek-link">Crypto regulation</a></h2>



Blockchain and its products are becoming an increasingly important part of our lives and our economies, which inevitably attracts the regulators’ attention. This is not a bad thing, though, for the right laws can support the technology and protect its users against related scams. Depending on a country however the attitude varies greatly, from progressive to autocratic. 



<h2>Beginner’s path </h2>



If you do not yet have a clear idea of what it is you would like to explore, let us suggest you a suite of 8 articles that will smoothly introduce you to the world of cryptoassets and Bitcoin in particular: it will help you to understand what it is used for, how it works and some necessary tools allowing to buy some of it.



<a href="https://d.center/explore/blockchain-philosophy" class="ek-link">Blockchain philosophy</a>



<a href="https://d.center/explore/bitcoin" class="ek-link">Bitcoin</a>



<a href="https://d.center/explore/how-does-bitcoin-work" class="ek-link">How does Bitcoin work</a>



<a href="https://d.center/explore/bitcoin-mechanism " class="ek-link">Bitcoin mechanism</a>



<a href="https://d.center/explore/blockchain-in-practice" class="ek-link">Blockchain in practice</a>



<a href="https://d.center/explore/blockhain-ecosystem" class="ek-link">Blockchain ecosystem</a>



<a href="https://d.center/explore/crypto-wallets" class="ek-link">Crypto wallets</a>



<a href="https://d.center/explore/crypto-exchanges " class="ek-link">Crypto exchanges</a>

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How are blockchains being used today? As a basis for cryptocurrencies sure, but also to decentralize traditional businesses and fuel the DeFi. All this brought to public by a well-developed ecosystem allowing anyone to use crypto. 



<h2>Cryptocurrency and Smart contract blockchains </h2>



With <a href="https://d.center/explore/bitcoin" class="ek-link">Bitcoin</a>, the first practical application of the blockchain was currency, or more precisely “P2P electronic cash system”, as described by Satoshi Nakamoto himself. Invented in order to remedy the defective monetary system, the blockchain proved itself to be particularly well suited for such a role, providing an independent, immutable and transparent transaction ledger.&nbsp;



Following Bitcoin, other <a href="https://d.center/explore/cryptocurrencies" class="ek-link">cryptocurrencies </a>have emerged, trying to ameliorate this or that aspect of the blockchain: transaction throughput, privacy… Other cryptocurrencies, namely stablecoins, focus on reducing price volatility. 



Before long people got a further idea to use the blockchain for more complex types of programs, leveraging its freedom from any trusted third party. These programs, called smart contracts, could be autonomous and self-execute when a predefined condition is triggered. An application running on a blockchain (dubbed DApp for “decentralized application”) cannot be modified once registered, not even by its creators. 



The first and most popular <a class="ek-link" href="https://d.center/explore/dapps-platforms">Smart contract platform</a> is Ethereum blockchain, however it also has its share of competitors. 



The difference between a Cryptocurrency blockchain and a Smart contract blockchain is now rather theoretical and can be spotted only by questioning the blockchain’s purpose: whether it was conceived to support a currency or to host elaborate smart contracts. Both types of blockchains need a native coin to pay the network nodes for running the protocol, however in cryptocurrencies’ case the native coin is a goal in itself, whereas for smart contract blockchains it is a payment for running smart contracts. 



In practice, Ethereum native coin ETH is often used as a currency, and Bitcoin can serve as payment for running Bitcoin-based smart contracts, which became possible thanks to the protocol and second layers development. Hence it is now better to speak more generally of cryptoassets as a whole. 



<h2>Blockchain use cases </h2>



The blockchain technology can be used in every sector that would profit from the absence of a trusted third party. Decentralized systems are intrinsically fairer than centralized ones, because they are much better in redistributing value and allow the users to be true and sole owners of their data. This quality is substantial when it comes to online platforms, whether for social media, cloud or ride hailing.



Blockchain being a transparent and immutable ledger, it is also particularly suitable for all data certification purposes.



Blockchain’s capacity to host smart contracts can automate numerous processes, not only increasing the overall cost and time effectiveness, but also providing users with a guarantee that no one will modify the conditions of a DApp using that smart contracts.&nbsp;



Finally, blockchain structure allows fast and easy data and values transfer, without any consideration for borders or other limitations. This quality is not only highly appreciated in the finance world, but can also be used to transfer digitized ownership rights for any type of value.&nbsp; 



<h2>Blockchain ecosystem </h2>



Blockchain is a collective endeavor, and it needs an extensive ecosystem to function and to serve its purposes. Numerous products and services have therefore been developed: <a href="https://d.center/explore/crypto-wallets" class="ek-link">wallets </a>to interact with a blockchain, <a href="https://d.center/explore/crypto-exchanges" class="ek-link">exchanges</a><a href="https://d.center/explore/crypto-exchanges" class="ek-link"> </a>to buy and sell crypto, oracles to interact with the real world and feed information to smart contracts, not to mention the miners who maintain the network or interoperability protocols connecting different blockchains. 



<h2>Blockchain in finance </h2>



Finance is a sector embracing the blockchain like no other. Traditional finance manipulates cryptoassets as a new type of value, incorporating it into the existing circuits, whereas the new type of finance - the DeFi (for decentralized finance) is taking shape.&nbsp;

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Smart contract platforms are called blockchain 2.0: they allow the creation of tokens and DApps, opening the blockchain to various use cases. 



The blockchain being essentially a piece of software run on a decentralized network, it can host not only the algorithms covering transaction logic, but also more complex ones.&nbsp;



The first blockchain - <a href="https://d.center/explore/bitcoin" class="ek-link">Bitcoin </a>- enabled transactions like “Alice sends a coin to Bob”, and other simple computational instructions, like “Alice will send a coin to Bob if Celine will agree on it”. These instructions are called  Smart contracts  - programs that auto-execute when triggered by a certain predefined condition - and were first theorized by Nick Szabo in 1995. Before long this idea was extended to more complex programs that could  be run in a decentralized way on blockchain. The first person to make this possible was Vitalik Buterin, creating in 2015 Ethereum blockchain - the first blockchain dedicated to smart contracts of different complexity.



<h2>Tokens</h2>



An important functionality that smart contracts logic can implement is token creation. In blockchain-speak a token is a digital unit representing any possible set of rights, assets or services attached to it, registered within a smart contract. Created on a blockchain, a token can then be freely exchanged on it, just like native cryptoassets. A token can serve as a form of currency, represent asset ownership or voting rights, or even an identity. Or all at once, depending on its purpose and developer’s imagination. With this, a new era begins - the token economy.



<h2>DApps </h2>



The applications using smart contracts were dubbed Decentralized applications, or DApps in short, since their execution is not controlled by any individual or central entity. A DApp is composed primarily of a user interface on the web and a smart contract deployed on the blockchain. Anyone using a DApp in fact initiates a transaction sent to the address of a smart contract on the blockchain, triggering smart contract execution, the resulting events being noted in the DApp’s logfile and registered on the blockchain. Generally such system makes DApps more secure than traditional applications: executed on a blockchain network instead of a private server, the possibility of an unsolicited third party intervention is much lower.&nbsp;



A direct consequence of decentralizing program execution is that once a smart contract is deployed on a blockchain, it cannot be modified, even by its creators. This property can bring additional value to a DApp (less opportunity for a DApp creator to cheat on its customers), but it also means that a special care should be taken when coding the smart contract.&nbsp;



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The DApps using smart contracts that need data outside of blockchain relies on oracles - third party data providers that trigger smart contract conditions. Oracles are generally agreed upon by both parties and written into the smart contract. For example, in case of a sports bet, an oracle will send the result of the match to the smart contract, which will execute itself and send a reward to the person who won the bet. Oracles’ development is tightly linked to the DApps success and adoption.



<h2>Smart contract platforms today</h2>



Since Ethereum, numerous smart contract-enabling blockchains have emerged, each with its own specificities. Cardano and EOS focus on scalability (number of transactions per second), the crucial aspect that needs to be improved in order to allow a widespread adoption of DApps. Tezos is reinventing the governance system, aiming at creating a self-amending blockchain. As to Tron, a blockchain with ambition to decentralize the online entertainment sector, it puts its best efforts to marketing.



These platforms and the DApps using them contribute to a wider use of the blockchain, finding yet more use cases and helping to decentralize the world.



<h2>Permissioned blockchains</h2>



Permissioned blockchains are another category of blockchains running smart contracts, used mainly by banks and enterprises when they do not wish to disclose some information or to have transaction immutability. These private or consortium blockchains speed up tedious verifications (for bank wires, for example) and help organise heterogeneous data across the companies working together (e.g. for supply chains). It is important to note though that permissioned blockchains are not independent and the information they contain can be modified by their owners.