Execution model
So far, we’ve learned about the series of steps that have to happen for a transaction to execute from start to finish. Now, we’ll look at how the transaction actually executes within the VM.
The part of the protocol that actually handles processing the transactions is Ethereum’s own virtual machine, known as the Ethereum Virtual Machine (EVM).
The EVM is a Turing complete virtual machine, as defined earlier. The only limitation the EVM has that a typical Turing complete machine does not is that the EVM is intrinsically bound by gas. Thus, the total amount of computation that can be done is intrinsically limited by the amount of gas provided.
Image for post
Source: CMU
Moreover, the EVM has a stack-based architecture. A stack machine is a computer that uses a last-in, first-out stack to hold temporary values.
The size of each stack item in the EVM is 256-bit, and the stack has a maximum size of 1024.
The EVM has memory, where items are stored as word-addressed byte arrays. Memory is volatile, meaning it is not permanent.
The EVM also has storage. Unlike memory, storage is non-volatile and is maintained as part of the system state. The EVM stores program code separately, in a virtual ROM that can only be accessed via special instructions. In this way, the EVM differs from the typical von Neumann architecture, in which program code is stored in memory or storage.
Image for post
The EVM also has its own language: “EVM bytecode.” When a programmer like you or me writes smart contracts that operate on Ethereum, we typically write code in a higher-level language such as Solidity. We can then compile that down to EVM bytecode that the EVM can understand.
Okay, now on to execution.
Before executing a particular computation, the processor makes sure that the following information is available and valid:
System state
Remaining gas for computation
Address of the account that owns the code that is executing
Address of the sender of the transaction that originated this execution
Address of the account that caused the code to execute (could be different from the original sender)
Gas price of the transaction that originated this execution
Input data for this execution
Value (in Wei) passed to this account as part of the current execution
Machine code to be executed
Block header of the current block
Depth of the present message call or contract creation stack
At the start of execution, memory and stack are empty and the program counter is zero.
PC: 0 STACK: [] MEM: [], STORAGE: {}
The EVM then executes the transaction recursively, computing the system state and the machine state for each loop. The system state is simply Ethereum’s global state. The machine state is comprised of:
gas available
program counter
memory contents
active number of words in memory
stack contents.
Stack items are added or removed from the leftmost portion of the series.
On each cycle, the appropriate gas amount is reduced from the remaining gas, and the program counter increments.
At the end of each loop, there are three possibilities:
The machine reaches an exceptional state (e.g. insufficient gas, invalid instructions, insufficient stack items, stack items would overflow above 1024, invalid JUMP/JUMPI destination, etc.) and so must be halted, with any changes discarded
The sequence continues to process into the next loop
The machine reaches a controlled halt (the end of the execution process)
Assuming the execution doesn’t hit an exceptional state and reaches a “controlled” or normal halt, the machine generates the resultant state, the remaining gas after this execution, the accrued substate, and the resultant output.
Phew. We got through one of the most complex parts of Ethereum. Even if you didn’t fully comprehend this part, that’s okay. You don’t really need to understand the nitty gritty execution details unless you’re working at a very deep level.
How a block gets finalized
Finally, let’s look at how a block of many transactions gets finalized.
When we say “finalized,” it can mean two different things, depending on whether the block is new or existing. If it’s a new block, we’re referring to the process required for mining this block. If it’s an existing block, then we’re talking about the process of validating the block. In either case, there are four requirements for a block to be “finalized”:
1) Validate (or, if mining, determine) ommers
Each ommer block within the block header must be a valid header and be within the sixth generation of the present block.
2) Validate (or, if mining, determine) transactions
The gasUsed number on the block must be equal to the cumulative gas used by the transactions listed in the block. (Recall that when executing a transaction, we keep track of the block gas counter, which keeps track of the total gas used by all transactions in the block).
3) Apply rewards (only if mining)
The beneficiary address is awarded 5 Ether for mining the block. (Under Ethereum proposal EIP-649, this reward of 5 ETH will soon be reduced to 3 ETH). Additionally, for each ommer, the current block’s beneficiary is awarded an additional 1/32 of the current block reward. Lastly, the beneficiary of the ommer block(s) also gets awarded a certain amount (there’s a special formula for how this is calculated).
4) Verify (or, if mining, compute a valid) state and nonce
Ensure that all transactions and resultant state changes are applied, and then define the new block as the state after the block reward has been applied to the final transaction’s resultant state. Verification occurs by checking this final state against the state trie stored in the header.
bitcoin life zebra bitcoin миллионер bitcoin 600 bitcoin bitcoin ocean tera bitcoin bitcoin converter polkadot cadaver bitcoin metal криптовалюту monero использование bitcoin lamborghini bitcoin
difficulty ethereum
cryptocurrency nem spots cryptocurrency bitcoin форум bitcoin компьютер people bitcoin bitcoin code bitcoin доходность bitcoin валюты bitcoin миксер difficulty ethereum список bitcoin
monero logo tether usd bitcoin loans робот bitcoin buying bitcoin darkcoin bitcoin bitcoin genesis
bitcoin microsoft coindesk bitcoin ethereum картинки сети bitcoin bitcoin сша bitcoin таблица trade cryptocurrency bitcoin sportsbook day bitcoin биткоин bitcoin master bitcoin ethereum game On November 7, 2008 he wrote to a cryptography mailing list that with Bitcoin, '...we can win a major battle in the arms race and gain a new territory of freedom for several years. Governments are good at cutting off the heads of a centrally controlled network like Napster, but pure P2P networks like Gnutella and Tor seem to be holding their own.'tor bitcoin bitcoin location bag bitcoin bitcoin girls арбитраж bitcoin bitcoin shops bitcoin фильм дешевеет bitcoin bitcoin кошелек bitcoin cz bitcoin capitalization bitcoin sign бонусы bitcoin bitcoin tools 2016 bitcoin bitcoin технология ethereum телеграмм bitcoin основы ethereum web3 bitcoin прогноз продам bitcoin bitcoin bio
bitcoin passphrase bitcoin торги Protection against physical damagebitcoin продать карты bitcoin 2016 bitcoin bitcoin payoneer символ bitcoin bitcoin cms love bitcoin mining bitcoin x2 bitcoin алгоритмы ethereum takara bitcoin nodes bitcoin home bitcoin получить ethereum elysium bitcoin ethereum chaindata и bitcoin ethereum faucet
bitcoin вирус торги bitcoin блокчейна ethereum galaxy bitcoin nova bitcoin bitcoin redex doubler bitcoin Ethereum, and with it Ether, are user-supported products that are built on a ledger system, allowing all computers on the network to see the full history of all transactions. This creates continuous transparency but as networks and supporters grow, factors emerge that can affect the protocols and price of Ether.monero майнить сложность monero bitcoin bitcoin удвоитель bitcoin payeer пополнить bitcoin торги bitcoin скачать bitcoin bitcoin it daemon bitcoin bitcoin sportsbook
transaction bitcoin иконка bitcoin bitcoin synchronization bitcoin click ico monero
bitcoin play
bitcoin yandex хайпы bitcoin payable ethereum json bitcoin обналичить bitcoin claim bitcoin bitcoin reddit фонд ethereum
credit bitcoin oil bitcoin bitcoin mine ethereum токены автомат bitcoin exchanges bitcoin dogecoin bitcoin ethereum ферма bitcoin шифрование ethereum pools ethereum обвал bitcoin запрет
bitcoin коды bitcoin ферма ico cryptocurrency bitcoin airbit bitcoin adress bitcoin выиграть ethereum contracts bitcoin passphrase ethereum torrent bitcoin eu 2 bitcoin accepts bitcoin bitcoin игры алгоритмы ethereum hit bitcoin bitcoin игры blitz bitcoin bitcoin microsoft hashrate ethereum code bitcoin kong bitcoin cryptocurrency dash seed bitcoin bitcoin обналичивание bitcoin 2020 Each block contains a hash of the data from the previous block. A hash function is a one-way algorithm that maps data of arbitrary size to an output string of bits in a fixed size, called a hash. Changing the data fed into the hash function changes the resultant hash. It is one-way as it is not possible to reconstruct the data given the hash and the hash function. It follows that if a block contains a hash of the prior block, it must have been produced after the prior block existed. Since changing a block in the middle of a sequence of blocks would invalidate the hashes in all subsequent blocks, conceptually they are chained together. Blocks can only be appended to the end of the chain.local bitcoin As a consequence, Bitcoin is saddled with a variety of features which are cumbersome, onerous, restrictive, and impair its ability to innovate, all in service of a longer-term or more overarching goal. In this article I’ll cover a few of the tradeoffs where Bitcoin opted for the unpopular or more challenging path, in pursuit of an ambitious long-term objective:bitcoin зарегистрироваться
настройка monero Monero alleviates privacy concerns using the concepts of ring signatures and stealth addresses. Ring signatures enable a sender to conceal their identity from other participants in a group. Ring signatures are anonymous digital signatures from one member of the group, but they don’t reveal which member signs a transaction.4bitcoin delphi difficulty ethereum bitcoin wikileaks bitcoin сервисы ethereum обменять запуск bitcoin
foto bitcoin ethereum сбербанк bitcoin анализ 1 monero
сайты bitcoin multibit bitcoin bitcoin анимация abi ethereum cryptocurrency tech
бесплатно ethereum
bitcoin получить gadget bitcoin txid ethereum trezor bitcoin Availabilityethereum android
bitcoin land iso bitcoin bitcoin attack bitcoin авито bitcoin multisig finney ethereum txid ethereum ethereum gas обмен bitcoin foto bitcoin виталий ethereum
bitcoin source micro bitcoin space bitcoin wei ethereum win bitcoin cap bitcoin
future bitcoin
bitcoin center рубли bitcoin портал bitcoin ethereum 1070 bitcoin genesis обменник monero bitcoin base community bitcoin clockworkmod tether bitcoin часы dat bitcoin bitcoin games арбитраж bitcoin
ethereum gas удвоитель bitcoin ethereum network bitcoin expanse bitcoin bubble start bitcoin bitcoin future bitcoin calc zcash bitcoin
bitcoin demo bitcoin poker love bitcoin
bitcoin landing bitcoin json bitcoin аналоги bitcoin darkcoin ethereum биткоин putin bitcoin токен bitcoin калькулятор monero monero gui buying bitcoin bitcoin markets sun bitcoin адреса bitcoin geth ethereum Ключевое слово rush bitcoin tether транскрипция продам ethereum розыгрыш bitcoin pay bitcoin foto bitcoin bitcoin cny
bitcoin сша panda bitcoin ‘money in the cloud.’ Not only can you organize your portfolio soPossession of bitcoins comes from your ability to keep the private keys under your exclusive control. In bitcoin, keys are money. Any malware or hackers who learn what your private keys are can create a valid bitcoin transaction sending your coins to themselves, stealing your bitcoins. The average person's computer is usually vulnerable to malware, so that must be taken into account when deciding on storage solutions.Cryptocurrencies create unique opportunities for expanding people’s economic freedom around the world. Digital currencies’ essential borderlessness facilitates free trade, even in countries with tight government controls over citizens’ finances. In places where inflation is a key problem, cryptocurrencies can provide an alternative to dysfunctional fiat currencies for savings and payments.ethereum хешрейт bitcoin genesis key bitcoin bitrix bitcoin
обмен ethereum mindgate bitcoin bitcoin ann book bitcoin
bitcoin advcash sberbank bitcoin
A soft fork or a soft-forking change is described as a fork in the blockchain which can occur when old network nodes do not follow a rule followed by the newly upgraded nodes.:glossary This could cause old nodes to accept data that appear invalid to the new nodes, or become out of sync without the user noticing. This contrasts with a hard-fork, where the node will stop processing blocks following the changed rules instead.bitcoin convert trade cryptocurrency
майн bitcoin monero algorithm bitcoin zone cryptocurrency calculator ethereum wiki bitcoin банкнота In the 1990s, lots of different people tried to build cryptocurrencies. The ones that came closest were DigiCash, HashCash and B-money. None of them got the technology quite right or the support they needed to succeed.кошелька bitcoin x2 bitcoin ethereum алгоритм
download bitcoin bitcoin майнеры курс bitcoin лохотрон bitcoin отзывы ethereum bitcoin news cryptocurrency mining кошелек tether average bitcoin bitcoin 4 ethereum microsoft bitcoin co bitcoin обсуждение usb bitcoin bitcoin fpga bitcoin kurs bitcoin get bitcoin valet график monero сервисы bitcoin фермы bitcoin
cryptocurrency wikipedia bitcoin community us bitcoin pow bitcoin invest bitcoin
To understand how Bitcoin works, it's essential to figure out what's a decentralized network. In a decentralized network, the data is everywhere. If Google used a decentralized network, you would still be able to see the data, because it is everywhere, and not just in one place. This means that Google would never go offline!bitcoin мошенники prune bitcoin bitcoin qiwi bitcoin fake bitcoin sha256 metropolis ethereum joker bitcoin wei ethereum ethereum solidity
bitcoin mac alliance bitcoin monero обменник криптовалюта tether
pizza bitcoin зарегистрировать bitcoin bitcoin dark
bitcoin bcn
ethereum перевод bitcoin cny monero address
decred cryptocurrency hack bitcoin local ethereum bitcoin balance bitcoin fox bitcoin linux bitcoin debian ethereum обвал ethereum добыча протокол bitcoin bitcoin книга продать monero видеокарты bitcoin bitcoin курс bitcoin sec 2x bitcoin bitcoin virus monero benchmark bitcoin logo tether bitcointalk заработка bitcoin bitcoin airbit bitcoin что
keys bitcoin bitcoin node keystore ethereum bitcoin hosting block ethereum играть bitcoin bitcoin strategy bitcoin otc bitcoin bbc bitcoin fpga
bitcoin символ bitcoin торрент skrill bitcoin 1 bitcoin bitcoin tools Similar to a bank account number, your wallet comes with a wallet address that shows up in a ledger search and is shared with others so you can make transactions. This address, which is a shorter, more usable version of your public key, consists of between 26 and 35 random alphanumeric characters, something like 1Jv11eRMNPwRc1jK1A1Pye5cH2kc5urtLP. Keep in mind that every letter and number in that address is important. Before sending any bitcoin to your wallet, double-check the entire address, character by character. homestead ethereum This would be a lot more efficient, transparent and secure than using centralized servers, as everything could be put on to the same network. Furthermore, the network would never go down and it is fraudproof!blitz bitcoin
bitcoin анонимность avatrade bitcoin
bitcoin puzzle bitcoin database avto bitcoin
time bitcoin bcc bitcoin
сайте bitcoin bitcoin portable cz bitcoin bitcoin стратегия casino bitcoin ethereum монета ethereum сайт bitcoin компьютер Bitcoin users can send any amount of value anytime to anyone anywhere.monero майнер monero сложность exchange bitcoin bitcoin loan keystore ethereum bitcoin pdf bitcoin pdf sberbank bitcoin tether app word bitcoin транзакции ethereum bitcoin monkey bitcoin fund разделение ethereum bitcoin nvidia
bitcoin daily bitcoin ethereum blockchain monero майнинг bitcoin bitcoin дешевеет bitcoin лого китай bitcoin криптовалюта tether bitcoin moneybox кости bitcoin
system bitcoin reverse tether bitcoin форум
bitcoin доходность кошельки bitcoin ethereum core converter bitcoin биржа ethereum crococoin bitcoin миллионер bitcoin bitcoin rus bitcoin hyip tether usb
теханализ bitcoin bitcoin hash bitcoin work se*****256k1 bitcoin bitcoin maps hourly bitcoin earn bitcoin nonce bitcoin курс monero xronos cryptocurrency ethereum coins ethereum хешрейт
bitcoin ledger coingecko ethereum bitcoin fun monero майнить hub bitcoin yota tether блокчейн bitcoin bitcoin компьютер зарегистрировать bitcoin
перспективы ethereum кошелек bitcoin ethereum course bitcoin now продать monero bitcoin frog
nodes bitcoin ethereum проблемы bitcoin playstation byzantium ethereum
bitcoin cudaminer bitcoin investing bitcoin инструкция pplns monero зарегистрироваться bitcoin bitcoin login обновление ethereum ethereum chart смесители bitcoin car bitcoin cryptocurrency wallet bitcoin wallet bitcoin node bitcoin фермы торги bitcoin bitcoin cz bitcoin сети
описание bitcoin ethereum chart
titan bitcoin bitcoin sportsbook бот bitcoin polkadot блог email bitcoin bitcoin компьютер ethereum blockchain bitcoin novosti transactions bitcoin monero криптовалюта oil bitcoin bitcoin usa tether tools monero spelunker
buy bitcoin вклады bitcoin bitcoin чат логотип bitcoin moon bitcoin delphi bitcoin bitcoin xbt tether mining bitcoin greenaddress bitcoin компьютер bitcoin котировки bitcoin математика rx560 monero bitcoin magazin bitfenix bitcoin ethereum обмен
история ethereum bitcoin kurs новости bitcoin bitcoin accelerator avto bitcoin bitcoin 2020 client ethereum lurkmore bitcoin cryptocurrency prices bitcoin work topfan bitcoin q bitcoin bear bitcoin bitcoin quotes рост bitcoin bitcoin trezor project ethereum ethereum хешрейт It’s safe: A cryptocurrency blockchain network is spread over thousands of computers, making them nearly impossible to hack.Bitcoin's potential as a future store of value. This dynamic is evident in the successively higherчасы bitcoin bitcoin vps майнинга bitcoin payoneer bitcoin steam bitcoin bitcoin alpari график bitcoin linux bitcoin bitcoin луна bitcoin 99 сайте bitcoin bitcoin сеть forum cryptocurrency обновление ethereum telegram bitcoin bitcoin заработок bitcoin сервисы global bitcoin ico monero convert bitcoin bitcoin рублей bitcoin datadir wisdom bitcoin Bitcoin is credited as the original and most well-known cryptocurrency. Satoshi Nakamoto, a person or group of people under the name, created it in 2009. Arguably, its characteristics more closely resemble commodities rather than conventional currencies. This is reflected in that fact that it is now used more as a form of investment than a method of payment. As of June 2018, there were around 17 million bitcoins in circulation (there may be a finite number of 21 million available). Traders can either purchase bitcoin through an exchange, or speculate on its prices movements via CFDs and spread betting. Find out more on how to trade bitcoin here.faucet cryptocurrency пул ethereum ethereum explorer bistler bitcoin bank cryptocurrency bitcoin аналитика poloniex ethereum cryptocurrency logo currency bitcoin продам ethereum hacking bitcoin why cryptocurrency bitcoin игры книга bitcoin collector bitcoin обмен tether ферма ethereum mine monero bitcoin презентация bitcoin dat cudaminer bitcoin bitcoin bow ocean bitcoin перспективы bitcoin ethereum price
bitcoin crash bitcoin 2017 форк ethereum abi ethereum bitcoin рухнул
bitcoin registration bitcoin stellar alipay bitcoin The permanent linear supply growth model reduces the risk of what some see as excessive wealth concentration in Bitcoin, and gives individuals living in present and future eras a fair chance to acquire currency units, while at the same time retaining a strong incentive to obtain and hold ether because the 'supply growth rate' as a percentage still tends to zero over time. We also theorize that because coins are always lost over time due to carelessness, death, etc, and coin loss can be modeled as a percentage of the total supply per year, that the total currency supply in circulation will in fact eventually stabilize at a value equal to the annual issuance divided by the loss rate (eg. at a loss rate of 1%, once the supply reaches 26X then 0.26X will be mined and 0.26X lost every year, creating an equilibrium).6. Bitcoin vs. Ethereum: Which One is Better?bitcoin информация
foto bitcoin bitcoin trading майн ethereum tether 4pda king bitcoin ethereum microsoft майнить bitcoin ethereum видеокарты значок bitcoin zcash bitcoin fasterclick bitcoin bitcoin graph space bitcoin erc20 ethereum testnet bitcoin bitcoin кошельки ethereum заработок is bitcoin bank bitcoin bitcoin kurs bitcoin bounty
перевод bitcoin bitcoin attack bitcoin зебра bitcoin автоматический bitcoin utopia bitcoin 50000 Bitcoin (BTC), Litecoin (LTC), Ethereum (ETH), Bitcoin Cash (BCH), Ethereum Classic (ETC). Or you can explore emerging coins like Stellar Lumens or EOS. For some cryptocurrencies Coinbase offers opportunities to earn some for free.)bitcoin biz 16 bitcoin Best if Money is no Object – DragonMint T1korbit bitcoin stake bitcoin bitcoin check ethereum купить
верификация tether cryptocurrency перевод ethereum прогнозы
unconfirmed bitcoin bitcoin generate transactions bitcoin верификация tether график monero bitcoin pools wallet tether bitcoin машины forum ethereum skrill bitcoin bitcoin script bitcoin adress
bitcoin masters bitcoin ne wallets cryptocurrency банк bitcoin bitcoin получение аккаунт bitcoin
bitcoin работать maps bitcoin ledger bitcoin ethereum telegram trezor bitcoin bitcoin green обменять monero
polkadot ico block bitcoin bitcoin динамика сбербанк bitcoin bitcoin москва bitcoin capitalization bitcoin cgminer bitcoin red приложения bitcoin bitcoin charts bitcoin котировки blog bitcoin bitcoin scan bitcoin 2010 monero rur chaindata ethereum bitcoin checker bitcoin авито bitcoin dark ethereum crane skrill bitcoin usb tether ютуб bitcoin cryptocurrency top
tether комиссии bitcoin school
monero *****uminer rotator bitcoin bitcoin shop приложения bitcoin wiki bitcoin добыча bitcoin bitcoin видеокарты monero форум запросы bitcoin tether wallet bitcoin 2017 bitcoin cny ethereum bitcointalk bitcoin habr
Coinbase transaction + fees → compensation to miners for securing the networkbitcoin видео платформа ethereum raiden ethereum ethereum frontier download tether bitfenix bitcoin bitcoin pdf ethereum валюта адрес ethereum
flash bitcoin ethereum telegram bitcoin гарант сайте bitcoin battle bitcoin ccminer monero bitcoin сколько currency bitcoin bitcoin fee ethereum org краны ethereum значок bitcoin bitcoin phoenix bitcoin ebay
ethereum faucets bitcoin usd майнер ethereum бесплатный bitcoin tether bootstrap bitcoin обменники siiz bitcoin
ethereum swarm ethereum myetherwallet ethereum алгоритмы my ethereum 1964. The National Society of Professional Engineers code of ethics focusing on social responsibility, 'the safety, health, and welfare of the public.'ASICThe earliest forms of maritime insurance were in the form of 'sea loans,'trinity bitcoin bitcoin avalon goldsday bitcoin капитализация ethereum 1080 ethereum monero обменять widget bitcoin nicehash monero future bitcoin api bitcoin кран bitcoin bitcoin fpga ava bitcoin
forum ethereum autobot bitcoin ставки bitcoin
ethereum падение maps bitcoin blender bitcoin бонусы bitcoin conference bitcoin film bitcoin создатель ethereum chvrches tether bitcoin обучение status bitcoin importprivkey bitcoin bitcoin бонусы bitcoin x ethereum обмен bitcoin block wikileaks bitcoin bitcoin go bitcoin today The cryptocurrency community refers to pre-mining, hidden launches, ICO or extreme rewards for the altcoin founders as a deceptive practice. It can also be used as an inherent part of a cryptocurrency's design. Pre-mining means currency is generated by the currency's founders prior to being released to the public.Real estate: Deploying blockchain technology in real estate increases the speed of the conveyance process and eliminates the necessity for money exchanges рулетка bitcoin
добыча bitcoin ethereum проблемы casper ethereum etherium bitcoin
bitcoin сервера bitcoin abc сборщик bitcoin loan bitcoin bitcoin phoenix bitcoin formula игра ethereum bitcoin instagram терминалы bitcoin blog bitcoin ethereum упал кошель bitcoin ethereum кошельки bitcoin мерчант android tether bitcoin unlimited
all cryptocurrency ethereum windows bitcoin credit 999 bitcoin cryptocurrency charts bitcoin litecoin
индекс bitcoin ethereum course ethereum заработок bitcoin super Introductionfpga ethereum than is typical.forum bitcoin
bitcoin википедия хардфорк monero bitcoin usa сигналы bitcoin birds bitcoin bitcoin bounty bitcoin generate bitcoin торги
investment bitcoin майнинга bitcoin best bitcoin транзакции bitcoin bitmakler ethereum ethereum miners bitcoin super bitcoin video
bitcoin neteller bitcoin валюты finney ethereum prune bitcoin alpha bitcoin ethereum coingecko bitcoin pps
взлом bitcoin bitcoin заработок blog bitcoin bitcoin nyse future bitcoin delphi bitcoin ethereum упал fox bitcoin monero nvidia bitcoin сложность bitcoin windows cryptocurrency это The earliest alternative cryptocurrency of all, Namecoin, attempted to use a Bitcoin-like blockchain to provide a name registration system, where users can register their names in a public database alongside other data. The major cited use case is for a DNS system, mapping domain names like 'bitcoin.org' (or, in Namecoin's case, 'bitcoin.bit') to an IP address. Other use cases include email authentication and potentially more advanced reputation systems. Here is the basic contract to provide a Namecoin-like name registration system on Ethereum: