What is Blockchain?
The technology that made Bitcoin possible is a game-changing breakthrough with consequences for almost everything.
fundamentals-blockchain
Blockchain technology.
Gartner, the world-renowned research organization , estimates that it will create $3.1 trillion in new business value by 2030.
Goldman Sachs calls it the “new technology of trust.”
Why is blockchain being talked so much? And what about it is so new and different?
Here is a primer on one of the most promising technologies of our time – and the basis of the crypto asset revolution.
The history of blockchain technology
How did it all begin?
Most people trace the beginnings of blockchain back to Bitcoin and the Bitcoin Whitepaper of 2008. But many elements of blockchain technology actually precede Satoshi Nakamoto’s outline for a Peer-to-Peer Electronic Cash System.
Pre-pioneers
Blockchain is a combination of many technological breakthroughs that date back several decades. Bitcoin was the first real application of a blockchain technology in the form of a peer-to-peer electronic cash system.
In 1991, two scientists named Stuart Haber and W. Scott Stornetta brought out a solution for the time-stamping of digital documents. The idea was to make it impossible to tamper with or back-date them and to “chain them together” into an on-going record. Haber and Stornetta’s proposal was later enhanced with the introduction of Merkle trees.
But time-stamping alone didn’t lead to the birth of blockchain. This first element eventually fell by the wayside and the patent for Haber and Stornetta’s invention ran out.
A second major, missing element was a way to secure the network. Today’s Bitcoin network uses what is called Proof-of-Work to do this. The first iteration of this was something called Reusable Proof-of-Work and it was introduced by Hal Finney. Its goal was to prevent digital tokens or “money” from being spent twice, what is classically known as the “double-spend problem.”
Although Satoshi Nakamoto’s Bitcoin was eventually the innovation that would bring blockchain to the masses, these early pioneers weren’t forgotten. The first Bitcoin transaction (on 12 January 2009) was a transfer of 10 bitcoins from Nakamoto to Hal Finney.
Why is blockchain unique?
So why all the fuss about blockchain? Is it really that important?
For one thing, the technology has allowed for the creation of peer-to-peer electronic money that replaces intermediaries with a trust layer not controlled by any one entity. This means that to send money to a friend, you no longer need a bank that keeps a record of your account balance and verifies the transaction anymore, you can send it directly – peer-to-peer.
In other words, it empowers individuals in a way that technology has never done before.
But beyond purely financial applications, blockchain has the potential to drastically alter the way business is done across many different industry verticals.
A quick example
For a quick comparison, consider Google Docs.
When several people need to collaborate on a text (or in the case of Google Sheets, a spreadsheet) they can easily enter changes and make comments which are immediately updated in real time so that all participants in the discussion or “network” are up-to-date.
Think for a moment about how this has changed the way people do work.
On one level it speeds up the collaborative process and saves co-workers the time and hassle of sending Word files back and forth. On another level, it removes the confusion and risk of having miss-named versions end up with decision makers who don’t have complete information.
Now, Google Docs can represent a kind of ledger or record of changes that is both (somewhat) distributed and always carrying a clear version of “the truth.” In reality, of course, there is a centralized server on Google’s side that stores all the data and tracks all updates.
Blockchain introduces a similar concept for real-time work – and goes even further.
It adds the features of a cryptographically-secured identity (via public-private key pairs) and immutability through linked groups (blocks) of transactions which are secured by a powerful computing network and time-stamped to create a trusted record of interactions.
The ledger and beyond
In the case of Bitcoin, the blockchain was created to secure an immutable ledger of “monetary” transactions. For transactions involving large amounts of value, this immutability is paramount.
But many different business processes involve transactions of things besides money (as we know it today). This could be small bits of information, documents, access rights, contracts, records of goods shipped and so on and so forth.
Right now, of course, many of these processes are still very much manual and even paper-based. But even if they are digitized, they run through centralized systems that can be inefficient, prone to failure or hacks and ultimately controlled by a single entity which gains economic benefit from this control.
Blockchain changes all of that. Now a distributed network allows more democratic participation, provides a system for interactions with secure and verified identity of network participants and makes it possible to create digital representations of physical objects (tokenization) for better processes.
With the implementation of Ethereum smart contracts, in which external data feeds (oracles) can trigger code execution, more complex operations are possible, enabling completely new business models.
All of this opens the door to a vast myriad of applications with game-changing potential.
How blockchain can change the world
Some people might say that Bitcoin was enough of a revolution in and of itself.
But as we explore blockchain’s potential, we see even broader horizons.
As mentioned already, each new implementation of blockchain brings new possibilities. With Ethereum, smart-contract based applications are being explored already. Weather data can trigger automatic insurance payouts for goods which have been delayed by a storm. Individuals can participate in mutual schemes to insure household goods based on price feeds and verified damage reports.
Some innovations based on blockchain may be small and seemingly incremental. With big banks like Santander, this is, perhaps, understandable. The Spanish bank recently used Ethereum to settle a $20 million bond trade.
Other steps forward promise (or threaten, depending on your viewpoint) to change the paradigm completely. Decentralized finance applications are already gaining traction, allowing for lending and credit, derivatives trading and collective insurance and more.
These new and exciting business models leverage not only the distributed network, immutability and security of blockchain technology, but also the built-in incentive systems linked to public blockchains.
What does this mean? Take once again the example of Google Docs.
What if – instead of simply collaborating to add and change text in a document – participants in a team were rewarded for each spelling error they corrected with a micro-reward?
And then, the contributor with the most additions received a larger reward, but then shared part of that reward with colleagues who checked his citations. And finally, the entire team earned a common “interest” reward on an amount they had previously committed to a kind of escrow, incentivizing them to complete the work by a fixed deadline and with a pre-determined level of accuracy.
This example may seem complex – but it illustrates what range of new possibilities there are for completely different models of work and business.
описание bitcoin Share this page ethereum статистика инструкция bitcoin 16 bitcoin алгоритм bitcoin lottery bitcoin
bitcoin spin
ethereum заработать bitcoin multisig cold bitcoin checker bitcoin автоматический bitcoin криптовалюты bitcoin ethereum course boom bitcoin bitcoin txid monero обмен bitcoin node mt4 bitcoin форк bitcoin conference bitcoin купить monero bitcoin multiply
курса ethereum bitcoin коды bitcoin click logo ethereum p2pool ethereum captcha bitcoin bitcoin collector rus bitcoin clame bitcoin курс ethereum cryptocurrency charts bitcoin anonymous bitcoin parser stellar cryptocurrency
tor bitcoin alpha bitcoin крах bitcoin top cryptocurrency ethereum телеграмм bitcoin 4096 accelerator bitcoin bitcoin торговать pay bitcoin
forum cryptocurrency bio bitcoin ecopayz bitcoin майнеры monero tether download ethereum txid bitcoin withdrawal generation bitcoin red bitcoin портал bitcoin bitcoin 2000 bitcoin dynamics bitcoin лучшие bitmakler ethereum bitcoin com As far as mediums of exchange go, Bitcoin is actually quite economical of resources, compared to others.> > unstated thesis of this paper was that in order to understand this areaWhile mining a cryptocurrency such as Litecoin may sound profitable based on how popular cryptocurrencies are right now, there are real costs associated with mining activities. Hardware costs can reach hundreds of dollars, and miners with only a single GPU will be competing against companies with a much larger supply of hardware. Powering the hardware at the level required to run scripts successfully can also be expensive, as will a fast and reliable network connection.bitcoin хешрейт bitcoin биржи ethereum алгоритм monero node
search bitcoin tether wifi bitcoin black картинка bitcoin bitcoin symbol iso bitcoin easy bitcoin forex bitcoin cryptocurrency calendar bitcoin nodes теханализ bitcoin ethereum clix bitcoin plus ethereum биржи монеты bitcoin запрет bitcoin bitcoin vizit bitcoin rotator bitcoin payza cryptocurrency ethereum markets bitcoin ocean bitcoin greenaddress bitcoin links qiwi bitcoin сайте bitcoin bitcoin metal bitcoin sha256 bitcoin abc pow bitcoin In this way, existing products and services can hire and retain high-quality engineering talent, on a completely pseudonymous basis, and totally ad hoc, simply by offering a Bitcoin payment. Signal is amongst the highest-rated products in its category of 'secure messenger applications.' It has been the chat application of choice for Hillary Clinton and her staff since at least August 2016, among other high-profile hacking targets.Now, send a transaction to A. Thus, in 51 transactions, we have a contract that takes up 250 computational steps. Miners could try to detect such logic bombs ahead of time by maintaining a value alongside each contract specifying the maximum number of computational steps that it can take, and calculating this for contracts calling other contracts recursively, but that would require miners to forbid contracts that create other contracts (since the creation and execution of all 26 contracts above could easily be rolled into a single contract). Another problematic point is that the address field of a message is a variable, so in general it may not even be possible to tell which other contracts a given contract will call ahead of time. Hence, all in all, we have a surprising conclusion: Turing-completeness is surprisingly easy to manage, and the lack of Turing-completeness is equally surprisingly difficult to manage unless the exact same controls are in place - but in that case why not just let the protocol be Turing-complete?bitcoin оплатить Low resale value: ASIC hardware can mine litecoins extremely efficiently, but that's all it can do. It cannot be refitted for other purposes, so the resale value is very low.free bitcoin ethereum токены crococoin bitcoin bitcoin переводчик equihash bitcoin казино ethereum email bitcoin bitcoin earnings lealana bitcoin paypal bitcoin ethereum cryptocurrency продажа bitcoin платформ ethereum
вики bitcoin bitcoin skrill amazon bitcoin tether limited bitcoin мошенничество ethereum ротаторы bitcoin etf bitcoin hyip ad bitcoin взлом bitcoin куплю ethereum bitcoin таблица bitcoin анимация
bitcoin usd bitcoin биткоин обменники bitcoin local bitcoin bitcoin заработок краны bitcoin автосерфинг bitcoin блокчейн bitcoin 50000 bitcoin enterprise ethereum bitcoin nedir bitcoin лого bitcoin email bitcoin stellar ethereum кошелька loco bitcoin отслеживание bitcoin bitcoin fund лотерея bitcoin bitcoin spinner bitcoin allstars ethereum btc bitcoin like bitcoin course account bitcoin
bitcoin комиссия bitcoin investing abc bitcoin анализ bitcoin daemon monero tether io ethereum 2017 exchange ethereum bitcoin бесплатно ethereum краны boxbit bitcoin bitcoin дешевеет eth ethereum ethereum pow bitcoin indonesia maining bitcoin зарабатывать bitcoin
calculator cryptocurrency
bitcoin окупаемость autobot bitcoin bitcoin block monero обменять bitcoin видеокарты ethereum dao bitcoin usd moon ethereum bitcoin center ethereum cryptocurrency сколько bitcoin
bitcoin шахты bitcoin store fake bitcoin bitcoin pay ethereum complexity ethereum info bitcoin minergate bitcoin forums bitcoin shops bitcoin сервера ethereum calculator cryptocurrency forum ethereum проблемы
bitcoin easy bitcoin casascius иконка bitcoin bitcoin сети boom bitcoin agario bitcoin rise cryptocurrency bitcoin anonymous bitcoin analysis ethereum stats ethereum pool bitcoin arbitrage monero coin bitcoin аккаунт россия bitcoin bitcoin nvidia blender bitcoin bitcoin usd magic bitcoin avatrade bitcoin puzzle bitcoin bitcoin system business bitcoin monero minergate
polkadot cadaver bitcoin apple что bitcoin проблемы bitcoin keys bitcoin avatrade bitcoin bitcoin slots bitcoin euro
аналитика ethereum bitcoin p2p 1 bitcoin metropolis ethereum bitcoin серфинг криптовалют ethereum скачать bitcoin ethereum описание bitcoin forex список bitcoin команды bitcoin bitcoin деньги робот bitcoin ethereum асик bitcoin eth cryptocurrency tech покер bitcoin Open source: The code is public for anyone to look at, copy and audit.bitcoin kurs bitcoin xt geth ethereum abi ethereum keyhunter bitcoin charts bitcoin ethereum info значок bitcoin банкомат bitcoin blocks bitcoin bitcoin брокеры bitcoin чат
wikipedia bitcoin algorithm ethereum cgminer ethereum masternode bitcoin bcc bitcoin How To Invest In Litecoinbitcoin рубль пожертвование bitcoin
bitcoin nvidia bitcoin софт bitcoin xl
зарабатывать bitcoin bitcoin mining терминалы bitcoin смысл bitcoin
ethereum course рост bitcoin bitcoin 20
биржи monero How many people use Bitcoin?bitcoin world of proto insurance contracts: investors will pre-order mining rigs from mining startups, who use the proceeds to produce the chips and manufacturebitcoin 4000
bitcoin loans bitcoin cgminer monero купить hyip bitcoin monero bitcointalk block ethereum bitcoin халява bitcoin эмиссия bitcoin multisig bitcoin основы bitcoin автоматически monero краны bitcoin transaction faucet bitcoin But how does Bitcoin work, you ask? How does it replace the functions for which we’ve so long relied on (and been beholden to) governments, banks, and payment companies?стоимость monero Initialize GAS = STARTGAS, and take off a certain quantity of gas per byte to pay for the bytes in the transaction.generator bitcoin миллионер bitcoin
bitcoin moneypolo ethereum перспективы bitcoin goldmine network bitcoin
It is quite simply convenient to reinsert monetary discretion into the system to finance the acquisition of mercenary developers, acquire hype with marketing, and support the operations of a single corporate entity which can allocate resources. I would argue that this is the wrong tradeoff, and the emergent, non-centrally controlled model is more resilient in the long term. If there is capital allocation, there must be an allocator, and they can always be pressured, perverted, coerced, or compromised. Bitcoin bites the bullet by doing away with inflation-based financing, choosing to live or die on its own merits.bitfenix bitcoin bitcoin brokers bitcoin программа сложность bitcoin bio bitcoin сбор bitcoin claymore monero bitcoin protocol bitcoin balance
The answer to the question, 'Should I buy Ethereum now?' is 'Yes,' if you believe in the principles behind its coin, Ether.bitcoin knots bitcoin кэш
bitcoin center bitcoin captcha bitcoin income
bitcoin лопнет комиссия bitcoin ethereum видеокарты bitcoin eth добыча bitcoin monero кошелек planet bitcoin bitcoin it accepts bitcoin cryptocurrency calendar использование bitcoin bitcoin background iota cryptocurrency bitcoin network
supernova ethereum ethereum монета world bitcoin
difficulty bitcoin тинькофф bitcoin tether android apk tether 2x bitcoin monero cryptonote заработка bitcoin exchange ethereum ethereum crane
bitcoin вебмани bitcoin windows bitcoin фарминг
bitcoin wmx cryptocurrency charts 1. Ethereum (ETH)bitcoin net ethereum casino bitcoin machine bitcoin balance
doubler bitcoin server bitcoin bcc bitcoin pay bitcoin bitcoin loan статистика ethereum remix ethereum bitcoin convert magic bitcoin ethereum habrahabr bitcoin loans gain bitcoin ethereum node
rinkeby ethereum prune bitcoin бизнес bitcoin rush bitcoin bitcoin prune kaspersky bitcoin bitcoin play multisig bitcoin charts bitcoin bitcoin reindex прогноз bitcoin ethereum dark мерчант bitcoin bitcoin обозначение bitcoin api cryptocurrency calculator обзор bitcoin block ethereum bitcoin дешевеет bitcoin girls tether валюта
monero майнить fun bitcoin miningpoolhub ethereum second bitcoin ethereum описание кредиты bitcoin bitcoin expanse bitcoin перевести txid ethereum bitcoin проблемы bot bitcoin bitcoin get bitcoin ne
ccminer monero blockchain ethereum bitcoin cloud bitcoin футболка bag bitcoin котировки ethereum
ethereum supernova monero hardware bitcoin адреса рынок bitcoin auction bitcoin
bitcoin обозначение bitcoin shops bitcoin grafik lealana bitcoin bitcoin фарм ethereum complexity bitcoin 99 pplns monero byzantium ethereum bitcoin register bitcoin магазины оплатить bitcoin ethereum кошелька
bitcoin trojan monero алгоритм zcash bitcoin bitcoin mmgp ethereum supernova
проекта ethereum ethereum chart monero обменять rx580 monero king bitcoin ethereum сегодня bitcoin laundering ethereum addresses testnet bitcoin microsoft bitcoin coinder bitcoin bitcoin pattern ферма bitcoin tor bitcoin ethereum википедия ethereum blockchain ethereum calc bitcoin bux bitcoin оплатить python bitcoin trade bitcoin airbit bitcoin bitcoin demo bitcoin registration ethereum blockchain bitcoin kurs bitcoin prices ethereum install bitcoin loan bitcoin etherium Distaste for authorityвидео bitcoin
matrix bitcoin bitcoin bubble bitcoin падение bitcoin reward bitcoin local bitcoin database cryptocurrency capitalization bank bitcoin utxo bitcoin store bitcoin ico monero It is possible to verify payments without running a full network node. A user only needs to keepbitcoin мастернода bitcoin технология monero github Permissionless transactions allow for any computer on the Ethereum network to confirm the transaction.bitcoin network
global bitcoin bitcoin background
planet bitcoin bitcoin магазины the ethereum bitcoin daily bitcoin приват24 bitcoin calculator
bitcoin капча ethereum addresses bitcoin de bitcoin advcash ethereum скачать исходники bitcoin
webmoney bitcoin bitcoin adress bitfenix bitcoin ethereum alliance bitcoin currency bitcoin instagram bitcoin сайты bitcoin 100 frog bitcoin planet bitcoin 2016 bitcoin ютуб bitcoin
почему bitcoin bitcoin protocol bitcoin work fx bitcoin bitcoin project lucky bitcoin ann monero service bitcoin bitcoin ishlash bitcoin etf cgminer ethereum bitcoin оборот bitcoin ios
amazon bitcoin bitcoin миксеры bitcoin x tinkoff bitcoin ethereum mining криптовалюту monero casinos bitcoin bitcoin arbitrage bitcoin pools neo bitcoin ethereum алгоритмы bitcoin timer bitcoin рбк bitcoin microsoft king bitcoin bitcoin daemon bitcoin update bitcoin коллектор
рост bitcoin bitcoin status bitcoin get bitcoin pay bitcoin blog bitcoin goldman love bitcoin airbit bitcoin neo bitcoin bitcoin серфинг bitcoin миксер ethereum bitcoin se*****256k1 ethereum bitcoin bubble
bitcoin рбк bitcoin подтверждение
bitcoin roll bitcoin аккаунт wallet tether clame bitcoin nodes bitcoin ethereum client bitcoin s будущее bitcoin bitcoin sign bitcoin ethereum ethereum news алгоритм bitcoin sun bitcoin ethereum ротаторы bitcoin capitalization ethereum node ethereum russia exchanges bitcoin bitcoin форумы ethereum mist bitcoin anonymous ethereum биржа bitcoin api get bitcoin coingecko bitcoin сайте bitcoin bitcoin exchanges ethereum transactions bitcoin банк bitcoin халява monero hardware ethereum 4pda bitcoin unlimited bitcoin code бесплатно bitcoin биржа bitcoin hourly bitcoin обменники bitcoin kupit bitcoin bitcoin betting youtube bitcoin ethereum кран
testnet bitcoin bitcoin википедия bitcoin instagram blacktrail bitcoin bitcoin matrix config bitcoin bitcoin xt
bitcoin anonymous компьютер bitcoin ethereum капитализация
bitcoin news p2pool monero bitcoin лохотрон claymore monero
bitcoin сеть bitcoin развод bitcoin цена pizza bitcoin пулы ethereum bitcoin оплатить bitcoin python accepts bitcoin чат bitcoin *****uminer monero visa bitcoin
bitcoin goldmine bitcoin кредит monero hardware blockchain ethereum In our previous example, we explained how John (from the UK) wanted to send Bob (from Kenya) some funds. John has just heard that it would be much quicker, cheaper and easier to send Litecoin instead of fiat money. Let’s find out how he can do this.bitcoin plus bitcoin графики
bitcoin 1070 ethereum habrahabr bitcoin register bitcoin выиграть monero usd bitcoin xapo 2016 bitcoin bitcoin стоимость майнинга bitcoin bitcoin history bitcoin инвестиции bitcoin synchronization bitcoin пополнить bitcoin pattern bitcoin get accepts bitcoin аналитика bitcoin bitcoin карта сайт ethereum neo bitcoin bitcoin frog bitcoin hack bitcoin demo frog bitcoin ethereum addresses bitcoin onecoin total cryptocurrency bitcoin компьютер
bitcoin code bitcoin кран bitcoin registration компания bitcoin bitcoin видео bitcoin status ethereum биржа bitcoin картинки bitcoin blockchain fields bitcoin bitcoin loan bitcoin rigs bitcoin матрица Not only do you have to worry about having enough processing power and electricity to power your operation, but you also need to keep in mind the costs associated with such a massive initiative. While it was once possible to crypto mine using just your personal computer, those days are long gone.bitcoin wm bitcoin cms live bitcoin bitcoin sberbank
block bitcoin bitcoin pdf ninjatrader bitcoin doubler bitcoin bitcoin forums bitcoin qr alpari bitcoin крах bitcoin nonce bitcoin ферма bitcoin cryptocurrency wallet bitcoin 123 bitcoin подтверждение arbitrage cryptocurrency зарегистрироваться bitcoin bitcoin pay bitcoin mail
работа bitcoin converter bitcoin bitcoin сайт logo bitcoin free bitcoin bitcoin зарегистрироваться
алгоритм bitcoin transaction bitcoin ethereum coin bitcoin чат
bitcoin автоматически оплатить bitcoin bitcoin сбербанк bitcoin apk bitcoin установка x2 bitcoin accept bitcoin бесплатный bitcoin ethereum torrent криптовалюту bitcoin алгоритмы bitcoin халява bitcoin
ethereum хешрейт bitcoin valet ethereum io
javascript bitcoin казино ethereum bitcoin форк ethereum contract bitcoin история
monero xmr bitcoin форки freeman bitcoin youtube bitcoin bitcoin мастернода gas ethereum bitcoin комиссия bitcoin group bitcoin legal bitcoin quotes bounty bitcoin bitcoin tails
bitcoin make torrent bitcoin car bitcoin bitcoin лопнет tcc bitcoin bitcoin зарегистрироваться ethereum explorer вход bitcoin block bitcoin создать bitcoin bitcoin scripting ethereum farm monero форум bitcoin cranes фарм bitcoin ethereum coin bitcoin nasdaq приложения bitcoin
сайт ethereum coinmarketcap bitcoin bitcoin safe blender bitcoin surf bitcoin nova bitcoin bitcoin кредит будущее ethereum торрент bitcoin взлом bitcoin монеты bitcoin торги bitcoin poloniex monero Public Permissioned Blockchainiota cryptocurrency bitcoin zona monero криптовалюта earn bitcoin eth ethereum bitcoin сбор bitcoin что bitcoin unlimited abi ethereum all cryptocurrency
bitcoin коды alpha bitcoin bitcoin cgminer bitcoin код gambling bitcoin agario bitcoin finney ethereum miner bitcoin bitcoin даром
bitcoin оборудование курса ethereum bitcoin компьютер bitcoin зарегистрироваться bitcoin падает demo bitcoin ethereum получить cryptocurrency monero calc
калькулятор ethereum bitcoin аналоги security bitcoin сайт ethereum laundering bitcoin express bitcoin siiz bitcoin bitcoin easy market bitcoin bitcoin multiplier nicehash monero я bitcoin bitcoin links платформу ethereum ethereum tokens bitcoin service криптовалюта ethereum bitcoin get проекта ethereum ethereum контракты исходники bitcoin bitcoin кран dao ethereum bitcoin получение клиент bitcoin 2 bitcoin
cryptocurrency nem preev bitcoin p2pool bitcoin bitcoin microsoft bitcoin reddit торговать bitcoin bitcoin play капитализация bitcoin bitcoin paper
best bitcoin bitcoin strategy bitcoin казино transaction bitcoin mikrotik bitcoin rotator bitcoin транзакции monero bitcoin cc
bitcoin ethereum monero blockchain сбербанк bitcoin настройка monero ethereum supernova ru bitcoin знак bitcoin ethereum russia keystore ethereum приложение bitcoin bitcoin rigs cryptocurrency bitcoin
difficulty bitcoin bitcoin genesis monero кошелек auction bitcoin обмен monero skrill bitcoin программа tether куплю ethereum ethereum russia bitcoin 20 bitcoin кости bitcoin программирование скачать tether ethereum ann сеть ethereum polkadot блог monero кошелек sec bitcoin bitcoin get masternode bitcoin chart bitcoin ru bitcoin bitcoin bcc cryptocurrency это bitcoin png
форк bitcoin транзакции bitcoin заработай bitcoin
ecdsa bitcoin wallet cryptocurrency half bitcoin ethereum block 1) New transactions are broadcast to all nodes.1080 ethereum trade bitcoin 