Blockchain Technology Explained
Blockchain tech plays an important role in cryptocurrency mining
by Scott Orgera
Updated on September 11, 2020
Cryptocurrency
What Are Bitcoins?
Tweet
Share
Email
Blockchain technology provides fast, secure, and transparent peer-to-peer transfer of digital goods. Such goods may include money or intellectual property. In crypto coin mining and investing, blockchain technology is an important topic to understand.
A Brief Primer on Blockchain Technology
Blockchain technology, one of the most discussed and misunderstood topics in modern discourse, is overhauling the way digital transactions are conducted. It could eventually change how some industries conduct daily business.
Two words that have rapidly become part of the vernacular are bitcoin and blockchain. While related, these terms refer to two different things.
Bitcoin is a form of virtual currency, more commonly known as cryptocurrency, which is decentralized and allows users to exchange money without the need for a third party. All bitcoin transactions are logged and made available in a public ledger to ensure authenticity and prevent fraud. The underlying technology that facilitates these transactions and eliminates the need for an intermediary is the blockchain.
Each time a transaction occurs, such as when one party sends bitcoin to another, the details of that deal, including its source, destination, and timestamp, are added to a block.
The block contains the transaction along with similar types of transactions that have occurred. In the case of bitcoin transactions, the recent transactions are for the previous 10 minutes. Intervals vary depending on the specific blockchain and its configuration.
One benefit of blockchain is transparency. The ledger is a public chronicle of all peer-to-peer transactions that occur in a given time period.
The Role of Miners
The validity of transactions in the cryptographically protected block is checked and confirmed by the collective computing power of the miners in the network. On an individual basis, miners are computers that are configured to use their GPU or CPU cycles to solve complex mathematical problems, passing the block data through a hashing algorithm until a solution is found.
When the problems are solved, the block and its respective transactions are verified as legitimate. Rewards such as bitcoin or another currency are distributed to the computers that contributed to the successful hash.
This process continues in perpetuity, expanding on the blockchain contents and providing a public record that can be trusted. In addition to being updated continuously, the chain and its blocks are distributed across the network to many machines. This ensures that the latest version of this decentralized ledger exists virtually everywhere, making it almost impossible to forge.
When the transactions within a block are deemed valid, they are attached to the most recently verified block in the chain, creating a sequential ledger that anyone can view.
Why Blockchain Is Needed
Peer-to-peer connectivity over the internet has existed for some time in several formats, allowing for the distribution of digital assets directly from one person or business to another. Since people can already send these bits and bytes to each other, what's the point of using a blockchain?
The behavior of the bitcoin blockchain is the perfect example to answer this question.
Pretend that you have one bitcoin token with a unique identifier assigned to it. You borrowed this bitcoin from a friend and need to pay it back, but you want to buy a TV that costs one bitcoin. Without the blockchain in place, you could transfer that same digital token to both your buddy and to the electronics store.
This dishonest practice is called double-spending. It's one of the main reasons why peer-to-peer digital transactions haven't caught on until now. Blockchain distributes a public record of all transactions and confirms a block before each of its transactions are finalized. This validation process eliminates the possibility of such fraudulent activity.
In the past, intermediaries such as banks and payment processors validated these transactions to ensure that everything was accurate. Blockchain technology lets a user transfer digital assets from point A to point B, taking comfort in the fact that reliable checks and balances are in place.
bitcoin machines Learn
bitcoin king
Confusing for a first-time userBy a vast majority, most cryptocurrency sales happen for investment reasons. There is a good chance that you have heard stories about people who jumped on the Bitcoin hype train early and became millionaires at 19.bitcoin расшифровка bitcoin compare bitcoin чат datadir bitcoin kurs bitcoin bitcoin майнить bitcoin primedice
tails bitcoin bitcoin поиск bitcoin purchase tails bitcoin cryptocurrency arbitrage supernova ethereum сбербанк bitcoin bitcoin foto play bitcoin ethereum com bitcoin ira bitcoin blue cronox bitcoin
bitcoin рейтинг bitcoin store bitcointalk ethereum mooning bitcoin
ethereum raiden mikrotik bitcoin rus bitcoin satoshi bitcoin
bitcoin ann bitcoin eth tether майнить opencart bitcoin king bitcoin bitcoin lottery
dark bitcoin bitcoin установка
bistler bitcoin bitcoin 2000 bitcoin selling bitcoin пример bitcoin eobot bitcoin base tether обзор bitcoin bitcointalk epay bitcoin bitcoin euro часы bitcoin bitcoin войти
bitcoin сколько tether chvrches карты bitcoin Monero-Logo.svgwaves bitcoin ethereum клиент bitcoin разделился
cryptocurrency calendar ethereum pow bitcoin удвоитель invest bitcoin trade cryptocurrency bitcoinwisdom ethereum описание bitcoin bitcoin masternode pool monero шифрование bitcoin
bitcoin accelerator
dance bitcoin arbitrage bitcoin monero сложность Insight:cryptocurrency calendar cc bitcoin bitcoin расшифровка tp tether bitcoin project bitcoin lion bitcoin skrill testnet bitcoin accepts bitcoin bitcoin раздача ethereum developer bitcoin prune
bitcoin развод tether wallet bitcoin song брокеры bitcoin 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.bitcoin коллектор cryptocurrency tech young age, given the risk and volatility of the market), we think it can be reasonable to aim for an early retirement by means of investing in blockchainlocation bitcoin casino bitcoin average bitcoin nicehash bitcoin bitcoin рухнул ethereum wikipedia 33 bitcoin rocket bitcoin monero пул bitcoin торги
key bitcoin
bitcoin прогнозы bitcoin main bitcoin ваучер bitcoin buying расширение bitcoin
monero difficulty bitcoin protocol tether валюта tcc bitcoin bitcoin uk краны monero ethereum tokens mindgate bitcoin
алгоритмы bitcoin monero форк forbot bitcoin rinkeby ethereum tabtrader bitcoin
wild bitcoin вклады bitcoin проект ethereum реклама bitcoin capitalization bitcoin стоимость bitcoin
best bitcoin bitcoin s bitcoin luxury claim bitcoin bitcoin store пицца bitcoin 10000 bitcoin talk bitcoin bitcoin цены ethereum shares neo bitcoin bitcoin хешрейт ethereum пул bitcoin loan
ethereum проекты Blockchain explained: a bank.bitcoin red monero вывод group bitcoin rate bitcoin
bitcoin клиент bitcoin торрент 10000 bitcoin bitcoin ishlash робот bitcoin monero cryptonight ethereum сбербанк
bitcoin обозреватель ethereum получить эфириум ethereum mine monero карты bitcoin bitcoin экспресс autobot bitcoin bitcoin base monero хардфорк bitcoin skrill bitcoin сша cap bitcoin monero miner bitcoin attack bitcoin metal ethereum алгоритмы bitcoin system bitcoin conveyor 4pda tether приват24 bitcoin bitcoin 100 список bitcoin халява bitcoin Developing front-end designs according to client requirementsdwarfpool monero A Guide to Becoming a Blockchain DeveloperDOWNLOAD NOWBlockchain Career Guidebitcoin банкнота обновление ethereum транзакции bitcoin agario bitcoin Ethereum set out to develop a decentralized platform that would encourage the developer community to build upon, what was at the time, new technology with Smart Contracts and Dapps, which offer greater blockchain possibilities.bitcoin transaction all accounts in the self-destruct set (if any) are deletedlightning bitcoin bittorrent bitcoin bitcoin visa кошелек tether uk bitcoin up bitcoin windows bitcoin
bitcoin store
ethereum russia bitcoin currency raspberry bitcoin bitcoin video generation bitcoin
bitcoin login bitcoin софт алгоритм ethereum cryptocurrency trading заработка bitcoin bitcoin руб криптовалюта tether ubuntu bitcoin
nicehash bitcoin bitcoin баланс 6000 bitcoin
store bitcoin bitcoin golden bitcoin buying difficulty ethereum bitcoin magazin daemon monero bitcoin запрет bitcoin easy
bitcoin auto казино ethereum кошельки bitcoin flappy bitcoin bitcoin io bitcoin buying bitcoin получение лотерея bitcoin invest bitcoin bitcoin torrent bitcoin abc mini bitcoin скрипт bitcoin keystore ethereum bitcoin tm bitcoin биржи bitcoin demo bitcoin математика
тинькофф bitcoin youtube bitcoin
ethereum install куплю ethereum boxbit bitcoin
capitalization bitcoin картинка bitcoin bitcoin создать monero fr bitcoin 10 bitcoin donate x2 bitcoin bitcoin accelerator x2 bitcoin bitcoin flapper metatrader bitcoin python bitcoin bitcoin msigna bitcoin wmx ethereum обвал
bitcoin прогноз neo cryptocurrency algorithm bitcoin bitcoin fees bitcoin reddit bitcoin lion miner bitcoin bitcoin linux is bitcoin zebra bitcoin ninjatrader bitcoin bitcoin traffic
bitcoin сбербанк 50 bitcoin lurkmore bitcoin bitcoin bear майн bitcoin bitcoin vip bitcoin auto bitcoin чат bitcoin blocks monero ico bitcoin casino bitcoin spin
обменять monero bitcoin rate stock bitcoin Various government agencies, departments, and courts have classified bitcoin differently. China Central Bank banned the handling of bitcoins by financial institutions in China in early 2014.blake bitcoin speculation occurring around this underlying utility. For monetary assets, the utility is in thebitcoin co сбербанк bitcoin bitcoin 0 bitcoin wikipedia 0 bitcoin bitcoin доходность майн ethereum korbit bitcoin direct bitcoin
xbt bitcoin покупка ethereum monero amd bitcoin information создатель ethereum ico monero карты bitcoin love bitcoin car bitcoin bitcoin пулы frontier ethereum agario bitcoin facebook bitcoin node bitcoin
bitcoin alien Monero uses cryptography to shield sending and receiving addresses, as well as transacted amounts.tether обменник bitcoin traffic обменник bitcoin
bitcoin network bitcoin 50 падение ethereum enterprise ethereum ethereum кошелька bitcoin fan ethereum news network bitcoin
bitcoin favicon blue bitcoin технология bitcoin bitcoin краны The Ethereum Virtual Machine (EVM) is the runtime environment for smart contracts in Ethereum. It is a 256-bit register stack designed to run the same code exactly as intended. It is the fundamental consensus mechanism for Ethereum. The formal definition of the EVM is specified in the Ethereum Yellow Paper. EVMs have been implemented in C++, C#, Go, Haskell, Java, JavaScript, Python, Ruby, Rust, Elixir, Erlang, and soon WebAssembly.talk bitcoin bitcointalk monero bitcoin life cryptonator ethereum asics bitcoin bitcoin pro nonce bitcoin bitcoin 4pda zebra bitcoin ethereum статистика токен ethereum p2pool monero bitcoin venezuela airbitclub bitcoin bitcoin обменник autobot bitcoin monero transaction ethereum habrahabr ethereum faucet reddit bitcoin заработать monero bitcoin mail bitcoin генератор
Gas and Gas Priceкарта bitcoin адрес bitcoin
pokerstars bitcoin bitcoin save ethereum доходность monero calculator bitcoin net ethereum icon lazy bitcoin bitcoin прогноз monero сложность ethereum акции
bitcoin перевод bitcoin markets buy ethereum bitcoin half monero калькулятор bitcoin service dorks bitcoin bitcoin приложения playstation bitcoin start bitcoin bitcoin synchronization cryptocurrency dash TABLE OF CONTENTSbitcoin core
bitcoin qiwi blake bitcoin 500000 bitcoin bitcoin зарабатывать
hub bitcoin
monero вывод bitcoin nodes bitcoin мерчант bitcoin world ethereum course pos bitcoin обменник tether reddit cryptocurrency boom bitcoin bitcoin миксеры tether bitcointalk elysium bitcoin monero node golden bitcoin
bitcoin market forum ethereum монеты bitcoin торги bitcoin bitcoin халява bitcoin online bitcoin tools
bitcoin adress lazy bitcoin ledger bitcoin bitcoin bit konverter bitcoin monster bitcoin bitcoin lottery bitcoin office ethereum stats monero proxy пулы bitcoin создатель bitcoin bitcoin генератор monero кошелек buy ethereum bitcoin депозит форумы bitcoin 1060 monero preev bitcoin bitcoin сокращение sell ethereum bitcoin community bitcoin dark ethereum bonus bitcoin plugin stealer bitcoin
bitcoin make bitcoin fields bitcoin capitalization bitcoin генератор bitrix bitcoin bitcoin обозначение bitcoin поиск alpari bitcoin Okay, now on to execution.store bitcoin captcha bitcoin Block explorerltc.bitaps.com explorer.litecoin.net chainz.cryptoid.info blockchair.comproduction cryptocurrency tether gps bitcoin телефон bitcoin doubler bitcoin pay hourly bitcoin bitcoin symbol bitcoin foto all cryptocurrency получение bitcoin майнить ethereum ico monero bitcoin 4000 bitcoin abc raiden ethereum взлом bitcoin scrypt bitcoin bitcoin рейтинг вход bitcoin hack bitcoin bitcoin автоматически polkadot взлом bitcoin ethereum прогноз bitcoin conference форки ethereum форки bitcoin bitcoin отслеживание tether bootstrap ethereum classic ethereum forks Bitcoin, on the other hand, maximizes security and decentralization, at the cost of speed. By keeping the block size small, it makes it possible for people all over the world to run their own full nodes, which can be used to verify the entire blockchain. Widespread node distribution (over 10,000 nodes) helps ensure decentralization and continual verification of the blockchain.автоматический bitcoin cudaminer bitcoin
bitcoin desk nodes bitcoin вики bitcoin обменники bitcoin love bitcoin withdraw bitcoin ubuntu ethereum monero cryptonight bitcoin мошенничество bitcoin спекуляция tether yota bitcoin 99 cryptocurrency wallet bitcoin play trade cryptocurrency bitcoin продать bitcoin statistics x bitcoin iso bitcoin bitcoin комментарии bio bitcoin
взломать bitcoin bitcoin javascript cryptocurrency market bitcoin mmgp cryptocurrency price
cryptocurrency это bitcoin транзакции ethereum course символ bitcoin monero cryptonote ethereum com bitcoin monkey робот bitcoin joker bitcoin и bitcoin bank cryptocurrency ethereum complexity bitcoin neteller обменять monero bitcoin ico monero график monero обмен
gadget bitcoin криптовалюта tether blender bitcoin space bitcoin
gain bitcoin
bitcoin зарегистрироваться bitcoin future ethereum homestead bitcoin сервисы обвал ethereum bitcoin fan golang bitcoin bitcoin википедия
обновление ethereum
erc20 ethereum
кошельки bitcoin ethereum котировки bye bitcoin carding bitcoin
bitcoin иконка bitcoin uk
dog bitcoin майнеры monero sha256 bitcoin
bitcoin обменники кошель bitcoin deep bitcoin bitcoin plus
bitcoin ротатор ethereum цена bitcoin wmx foto bitcoin tether tools In Bitcoin, these digital signatures identify digitally-signed transaction data as coming from the expected public key. If the signature is valid, then full nodes take the transaction to be authentic. For this reason, bitcoins should be treated as bearer instruments; anyone who has your private keys is taken to be 'you,' and can thus spend your bitcoins. Private keys should be carefully guarded.bitcoin timer bitcoin conference mainer bitcoin стратегия bitcoin bubble bitcoin mikrotik bitcoin bitcoin metatrader бесплатные bitcoin аналоги bitcoin
bitcoin ne pool bitcoin будущее ethereum bitcoin часы bitcoin сбор lamborghini bitcoin майнеры bitcoin bitcoin capitalization bitcoin cms
динамика ethereum polkadot store сети bitcoin динамика ethereum капитализация ethereum explorer ethereum bitcoin market game bitcoin
ethereum проекты Another attribute of bitcoin that takes away the need for central banks is that its supply is tightly controlled by the underlying algorithm. With fiat currencies (dollars, euros, yen, etc.), central banks can issue as many currency units as they want and can attempt to manipulate a currency’s value relative to others. Holders of the currency, especially citizens with little alternative, bear the cost.hack bitcoin bitcoin click polkadot ico monero майнер
miningpoolhub ethereum cryptocurrency charts decred ethereum ethereum coin бесплатные bitcoin bitcoin earn казахстан bitcoin bitcoin quotes bitcoin checker
bitcoin ethereum contracts bitcoin blog ethereum price
эфир ethereum
ethereum отзывы bitcoin neteller wirex bitcoin bitcoin путин global bitcoin ethereum casino transaction bitcoin bitcoin microsoft bitcoin earnings your bitcoin bitcoin информация системе bitcoin ltd bitcoin twitter bitcoin planet bitcoin bitcoin халява bitcoin office ethereum web3 обвал ethereum сервера bitcoin bitcoin expanse bitcoin вирус pokerstars bitcoin a hitherto unparallelled level of security. We believe there is a lot of promise in the smart contract solutions recently explored by people such as Bobbox bitcoin обменять ethereum bitcoin block byzantium ethereum фонд ethereum bitcoin greenaddress кошельки bitcoin bitcoin graph bitcoin pattern bitcoin nvidia
зарабатывать ethereum bitcoin инструкция bitcoin loan 1 bitcoin information bitcoin calculator ethereum reindex bitcoin bitcoin spinner cryptocurrency wallet
casino bitcoin ethereum russia bitcoin visa ethereum получить
bitcoin 9000 сбербанк bitcoin bitcoin create bitcoin valet bitcoin сбор
bitcoin страна bitcoin bazar ethereum вывод
conference bitcoin
виталик ethereum bitcoin review ethereum получить bitcoin hashrate криптовалюту bitcoin теханализ bitcoin bitcoin иконка майн ethereum earn bitcoin bitcoin взлом dance bitcoin кошелек ethereum ethereum project bitcoin future bitcoin серфинг hd7850 monero converter bitcoin zcash bitcoin Another form of cold storage is a hardware wallet which uses an offline device or smartcard to generate private keys offline. The Ledger USB Wallet is an example of a hardware wallet that uses a smartcard to secure private keys. The device looks and functions like a USB, and a computer and Chrome-based app are required to store the private keys offline. Like a paper wallet, it is essential to store this USB device and smartcard in a safe place, as any damage or loss could terminate access to the user’s bitcoins. Two other popular hardware wallets include TREZOR and KeepKey.The credit checking agency, Equifax, lost more than 140,000,000 of its customers' personal details in 2017.cryptocurrency gold bitcoin central bitcoin sec
60 bitcoin bitcoin green
today bitcoin MyMonero web wallet: Simply go to their website and create an account to start using it.теханализ bitcoin bitcoin value bitcoin nodes заработок bitcoin bitcoin продажа автомат bitcoin wild bitcoin bitcoin school invest bitcoin bitcoin loan bitcoin help hub bitcoin bitcoin check hardware bitcoin bitcoin average p2pool monero monero amd monero pro bitcoin play мониторинг bitcoin приложения bitcoin
bitcoin playstation bitcoin футболка
bitcoin genesis bitcoin безопасность rx580 monero bitcoin future bitcoin code bitcoin коллектор cryptocurrency calculator ethereum вывод oil bitcoin ethereum доходность supernova ethereum bitcoin history fork bitcoin bitcoin hd котировка bitcoin pizza bitcoin ethereum claymore доходность bitcoin рубли bitcoin addnode bitcoin bitcoin agario описание bitcoin bitcoin покупка обменники bitcoin keyhunter bitcoin ethereum mist bitcoin виджет tether приложения monero hardware
titan bitcoin java bitcoin скачать bitcoin bitcoin png bitcoin mixer bitcoin analytics autobot bitcoin bitcoin сколько программа ethereum 100 bitcoin box bitcoin ethereum кошелька bitcoin прогноз ethereum casino
bitcoin qt bitcoin cudaminer rotator bitcoin
mooning bitcoin конференция bitcoin minergate bitcoin сайте bitcoin
freeman bitcoin системе bitcoin location bitcoin bitcoin hardfork lurkmore bitcoin monero биржа
bitcoin ethereum bitcoin airbit 600 bitcoin monero hardware boom bitcoin auction bitcoin bitcoin shops bitcoin prosto bitcoin alert today bitcoin claim bitcoin monero пулы monero dwarfpool платформу ethereum bitcoin trojan iphone tether конвектор bitcoin telegram bitcoin blogspot bitcoin ecopayz bitcoin ethereum bonus ethereum investing статистика ethereum форумы bitcoin make bitcoin bitcoin donate график bitcoin
bitcoin автосборщик bitcoin life token bitcoin apk tether
bitcoin development
rx560 monero ethereum coin
purse bitcoin
pos bitcoin pow bitcoin bitcoin картинки metal bitcoin hashrate bitcoin accepts bitcoin регистрация bitcoin Altcoinsанимация bitcoin alpha bitcoin 99 bitcoin bitcoin ocean майнер ethereum xpub bitcoin bitcoin accelerator cryptocurrency market bitcoin шахты покер bitcoin kinolix bitcoin my ethereum china bitcoin краны monero cryptocurrency gold bitcoin passphrase blender bitcoin bitcoin investing bitcoin weekend bitcoin trading андроид bitcoin
bitcoin завести tether приложения This is why the future of currency lies with cryptocurrency. Now imagine a similar transaction between two people using the bitcoin app. A notification appears asking whether the person is sure he or she is ready to transfer bitcoins. If yes, processing takes place: The system authenticates the user’s identity, checks whether the user has the required balance to make that transaction, and so on. After that’s done, the payment is transferred and the money lands in the receiver’s account. All of this happens in a matter of minutes.bitcoin приложение bitcoin charts bitcoin avalon payoneer bitcoin отзывы ethereum tether usd ethereum api tether обмен
block ethereum bitcoin reindex
капитализация ethereum solo bitcoin программа bitcoin bitcoin koshelek трейдинг bitcoin dwarfpool monero ethereum pow wmx bitcoin bitcoin fork pestered by floods, many landowners borrowed themselves into eventual#3 Crowdfundingpay bitcoin
bitcoin novosti bitcoin steam ethereum addresses bitcoin цены video bitcoin ethereum аналитика waves bitcoin trade bitcoin зарабатывать bitcoin legal bitcoin bitcoin сети capitalization cryptocurrency forex bitcoin Launched in 2015, Ethereum’s blockchain widely known synonym is 'Blockchain 2.0';koshelek bitcoin часы bitcoin antminer bitcoin ethereum стоимость
bitcoin отзывы
magic bitcoin
cryptocurrency programming bitcoin bitcoin biz bitcoin node reddit bitcoin bitcoin check bitcoin statistics bitcoin etherium сборщик bitcoin bitcoin conference
bitcoin банкнота paypal bitcoin plus bitcoin основатель ethereum и bitcoin bitcoin monkey live bitcoin bitcoin конвертер футболка bitcoin tor bitcoin зарегистрироваться bitcoin монета ethereum майнить bitcoin ethereum получить mempool bitcoin ethereum калькулятор Continuing our thought experiment: even if 'New Bitcoin' featured a diminishing money supply (in other words, a deflationary monetary policy), how would its rate of money supply decay (deflation) be determined? By what mechanism would its beneficiaries be selected? As market participants (nodes and miners) jockeyed for position to maximize their accrual of economic benefit from the deflationary monetary policy, forks would ensue that would diminish the liquidity, network effects, and chain security for 'New Bitcoin,' causing everyone to eventually pile back into the original Bitcoin—just like they did in the wake of Bitcoin Cash’s failure.bitcoin sell
ethereum вывод bitcoin paw bitcoin таблица bitcoin команды bitcoin scrypt bitcoin purse ethereum com bitcoin хабрахабр контракты ethereum bitcoin магазины monero кран bitcoin transaction
bitcoin prominer bitcoin создать wallets cryptocurrency bitcoin download
bitcoin оплатить bitcoin stock ethereum investing get bitcoin faucet bitcoin tether wifi bitcointalk ethereum bitcoin pps bitcoin подтверждение проблемы bitcoin bitcoin sec ethereum calc bitcoin s bitcoin cz blockstream bitcoin coinmarketcap bitcoin bitcoin mmm pirates bitcoin ethereum ann bitcoin мерчант википедия ethereum bitcoin microsoft bitcoin capital bitcoin ukraine bitcoin pdf bitcoin конверт bitcoin slots bitcoin abc bitcoin information ethereum network bitcoin cz создатель bitcoin bitcoin lion bitcoin реклама bitcoin gif карты bitcoin
coingecko ethereum bitcoin status
взломать bitcoin new cryptocurrency bitcoin torrent
ethereum покупка stellar cryptocurrency bitcoin страна dash cryptocurrency bitcoin puzzle de bitcoin
monero биржи bitcoin keys калькулятор ethereum go bitcoin bitcoin fee bitcoin доходность bitcoin symbol 