Proof of work (PoW) is a form of cryptographic proof in which one party proves to others that a certain amount of a specific computational effort has been expended. Verifiers can subsequently confirm this expenditure with minimal effort on their part. The concept was invented by Moni Naor and Cynthia Dwork in 1993 as a way to deter denial-of-service attacks and other service abuses such as spam on a network by requiring some work from a service requester, usually meaning processing time by a computer. The term "proof of work" was first coined and formalized in a 1999 paper by Markus Jakobsson and Ari Juels.
Bitcoin is a decentralized digital currency. Bitcoin transactions are verified by network nodes through cryptography and recorded in a public distributed ledger called a blockchain. The cryptocurrency was invented in 2008 by an unknown entity under the name Satoshi Nakamoto. The currency began use in 2009, when its implementation was released as open-source software. The word "bitcoin" was defined in a white paper published on October 31, 2008. It is a compound of the words bit and coin.
A cryptocurrency, crypto-currency, or crypto is a digital currency designed to work as a medium of exchange through a computer network that is not reliant on any central authority, such as a government or bank, to uphold or maintain it. It is a decentralized system for verifying that the parties to a transaction have the money they claim to have, eliminating the need for traditional intermediaries, such as banks, when funds are being transferred between two entities.
Litecoin is a decentralized peer-to-peer cryptocurrency and open-source software project released under the MIT/X11 license. Inspired by Bitcoin, Litecoin was among the earliest altcoins, starting in October 2011. In technical details, the Litecoin main chain shares a slightly modified Bitcoin codebase. The practical effects of those codebase differences are lower transaction fees, faster transaction confirmations, and faster mining difficulty retargeting. Due to its underlying similarities to Bitcoin, Litecoin has historically been referred to as the "silver to Bitcoin's gold." In 2022, Litecoin added optional privacy features via soft fork through the MWEB upgrade.
The Bitcoin network is a peer-to-peer network of nodes which implement the Bitcoin protocol. The protocol itself implements a highly available, public, and decentralized ledger. The nodes verify that each update to the ledger follows the rules of the Bitcoin protocol.
Zerocoin is a privacy protocol proposed in 2013 by Johns Hopkins University professor Matthew D. Green and his graduate students, Ian Miers and Christina Garman. It was designed as an extension to the Bitcoin protocol that would improve Bitcoin transactions' anonymity by having coin-mixing capabilities natively built into the protocol. Zerocoin is not currently compatible with Bitcoin.
Ethereum is a decentralized blockchain with smart contract functionality. Ether is the native cryptocurrency of the platform. Among cryptocurrencies, ether is second only to bitcoin in market capitalization. It is open-source software.
Dash is an open source cryptocurrency. It is an altcoin that was forked from the Bitcoin protocol. It is also a decentralized autonomous organization (DAO) run by a subset of its users, which are called "masternodes".
A blockchain is a distributed ledger with growing lists of records (blocks) that are securely linked together via cryptographic hashes. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data. Since each block contains information about the previous block, they effectively form a chain, with each additional block linking to the ones before it. Consequently, blockchain transactions are irreversible in that, once they are recorded, the data in any given block cannot be altered retroactively without altering all subsequent blocks.
Monero is a cryptocurrency which uses a blockchain with privacy-enhancing technologies to obfuscate transactions to achieve anonymity and fungibility. Observers cannot decipher addresses trading Monero, transaction amounts, address balances, or transaction histories.
Ethereum Classic is a blockchain-based distributed computing platform which offers smart contract (scripting) functionality. It is open source and supports a modified version of Nakamoto consensus via transaction-based state transitions executed on a public Ethereum Virtual Machine (EVM).
Firo, formerly known as Zcoin, is a cryptocurrency aimed at using cryptography to provide better privacy for its users compared to other cryptocurrencies such as Bitcoin.
Bitcoin Cash is a cryptocurrency that is a fork of Bitcoin. Bitcoin Cash is a spin-off or altcoin that was created in 2017.
A cryptocurrency wallet is a device, physical medium, program or a service which stores the public and/or private keys for cryptocurrency transactions. In addition to this basic function of storing the keys, a cryptocurrency wallet more often offers the functionality of encrypting and/or signing information. Signing can for example result in executing a smart contract, a cryptocurrency transaction, identification, or legally signing a 'document'.
Bitcoin Gold (BTG) is a cryptocurrency. It is a hard fork of Bitcoin, the open source cryptocurrency. It is an open source, decentralized digital currency without a central bank or intermediary that can be sent from user to user on the peer-to-peer Bitcoin Gold network.
Cryptocurrency and crime describes notable examples of cybercrime related to theft of cryptocurrencies and some of the methods or security vulnerabilities commonly exploited. Cryptojacking is a form of cybercrime specific to cryptocurrencies that has been used on websites to hijack a victim's resources and use them for hashing and mining cryptocurrency.
IOTA is an open-source distributed ledger and cryptocurrency designed for the Internet of things (IoT). It uses a directed acyclic graph to store transactions on its ledger, motivated by a potentially higher scalability over blockchain based distributed ledgers. IOTA does not use miners to validate transactions, instead, nodes that issue a new transaction on the network must approve two previous transactions. Transactions can therefore be issued without fees, facilitating microtransactions. The network currently achieves consensus through a coordinator node, operated by the IOTA Foundation. As the coordinator is a single point of failure, the network is currently centralized.
A blockchain is a shared database that records transactions between two parties in an immutable ledger. Blockchain documents and confirms pseudonymous ownership of all transactions in a verifiable and sustainable way. After a transaction is validated and cryptographically verified by other participants or nodes in the network, it is made into a "block" on the blockchain. A block contains information about the time the transaction occurred, previous transactions, and details about the transaction. Once recorded as a block, transactions are ordered chronologically and cannot be altered. This technology rose to popularity after the creation of Bitcoin, the first application of blockchain technology, which has since catalyzed other cryptocurrencies and applications.
Nano is a cryptocurrency characterized by a directed acyclic graph data structure and distributed ledger, making it possible for Nano to work without intermediaries. To agree on what transactions to commit, it uses a voting system with weight based on the amount of currency an account holds.
Stacks, formerly Blockstack, is a blockchain platform for smart contracts, decentralized finance ("DeFi"), NFTs, and decentralized apps ("DApps"). Stacks blockchain is a layer for bitcoin similar to the Lightning Network.
