The validity of each cryptocurrency's coins is provided by a blockchain. A blockchain is a continuously growing list of records, called blocks, which are linked and secured using cryptography. Each block typically contains a hash pointer as a link to a previous block, a timestamp and transaction data. By design, blockchains are inherently resistant to modification of the data. It is "an open, distributed ledger that can record transactions between two parties efficiently and in a verifiable and permanent way". For use as a distributed ledger, a blockchain is typically managed by a peer-to-peer network collectively adhering to a protocol for validating new blocks.


bitcoinsbitcoin walletBitcoin blockchain
It is a decentralized digital currency without a central bank or single administrator that can be sent from user-to-user on the peer-to-peer bitcoin network without the need for intermediaries. Transactions are verified by network nodes through cryptography and recorded in a public distributed ledger called a blockchain. Bitcoin was invented by an unknown person or group of people using the name Satoshi Nakamoto and released as open-source software in 2009. Bitcoins are created as a reward for a process known as mining. They can be exchanged for other currencies, products, and services.


onlinethe Internetweb
Free and fee-based services exist for all of these activities, using centralized servers and distributed peer-to-peer technologies. Some of these sources exercise more care with respect to the original artists' copyrights than others. Internet usage has been correlated to users' loneliness. Lonely people tend to use the Internet as an outlet for their feelings and to share their stories with others, such as in the "I am lonely will anyone speak to me" thread.

Consensus (computer science)

consensusconsensus problemsdistributed consensus
Google has implemented a distributed lock service library called Chubby. Chubby maintains lock information in small files which are stored in a replicated database to achieve high availability in the face of failures. The database is implemented on top of a fault-tolerant log layer which is based on the Paxos consensus algorithm. In this scheme, Chubby clients communicate with the Paxos master in order to access/update the replicated log; i.e., read/write to the files. Bitcoin uses proof of work to maintain consensus in its peer-to-peer network.


EtherETHETH blockchain
Ethereum is an open-source, public, blockchain-based distributed computing platform and operating system featuring smart contract (scripting) functionality. It supports a modified version of Nakamoto consensus via transaction-based state transitions. Ether is a cryptocurrency whose blockchain is generated by the Ethereum platform. Ether can be transferred between accounts and used to compensate participant mining nodes for computations performed. Ethereum provides a decentralized virtual machine, the Ethereum Virtual Machine (EVM), which can execute scripts using an international network of public nodes.

Distributed networking

Distributed Network
A distributed network can also be agent-based, where what controls the agent or component is loosely defined, and the components can have either pre-configured or dynamic settings. Decentralization is where each computer on the network can be used for the computing task at hand, which is the opposite of the client/server model. Typically, only idle computers are used, and in this way, it is thought that networks are more efficient. Peer-to-peer (P2P) computation is based on a decentralized, distributed network, including the distributed ledger technology blockchain.

History of money

monetary historyabandonmentan international currency of the early ages
Its use of cryptography allowed the currency to have a trustless, fungible and tamper resistant distributed ledger called a blockchain. It became the first widely used decentralized, peer-to-peer, cryptocurrency. Other comparable systems had been proposed since the 1980s. The protocol proposed by Nakamoto solved what is known as the double-spending problem without the need of a trusted third-party. Since Bitcoin's inception, thousands of other cryptocurrencies have been introduced, many of which use the symbology of former metallic currencies, such as silver for Litecoin. In modern times economists have sort to classify the different types of money supply.


torrentBitTorrent protocoltorrents
In the 2010s, some P2P, decentralized alternatives to Torrent search engines have emerged, see decentralized keyword search below. The BitTorrent protocol is still under development and may therefore still acquire new features and other enhancements such as improved efficiency. On 2 May 2005, Azureus (now known as Vuze) was released, introducing support for "trackerless" torrents through a system called the "distributed database." This system is a Distributed hash table implementation which allows the client to use torrents that do not have a working BitTorrent tracker.

Parallel computing

parallelparallel processingparallelism
A distributed computer (also known as a distributed memory multiprocessor) is a distributed memory computer system in which the processing elements are connected by a network. Distributed computers are highly scalable. The terms "concurrent computing", "parallel computing", and "distributed computing" have a lot of overlap, and no clear distinction exists between them. The same system may be characterized both as "parallel" and "distributed"; the processors in a typical distributed system run concurrently in parallel. A cluster is a group of loosely coupled computers that work together closely, so that in some respects they can be regarded as a single computer.

Node (networking)

nodenodesnetwork node
If the network in question is a distributed system, the nodes are clients, servers or peers. A peer may sometimes serve as client, sometimes server. In a peer-to-peer or overlay network, nodes that actively route data for the other networked devices as well as themselves are called supernodes. Distributed systems may sometimes use virtual nodes so that the system is not oblivious to the heterogeneity of the nodes. This issue is addressed with special algorithms, like consistent hashing, as it is the case in Amazon's Dynamo.


C++ programming languageC++ standardC++ language
When Stroustrup started working in AT&T Bell Labs, he had the problem of analyzing the UNIX kernel with respect to distributed computing. Remembering his Ph.D. experience, Stroustrup set out to enhance the C language with Simula-like features. C was chosen because it was general-purpose, fast, portable and widely used. As well as C and Simula's influences, other languages also influenced C++, including ALGOL 68, Ada, CLU and ML. Initially, Stroustrup's "C with Classes" added features to the C compiler, Cpre, including classes, derived classes, strong typing, inlining and default arguments.

Decentralised system

decentralizeddecentralized systemdecentralised
Examples of decentralized systems: Examples of "decentralized system culture": Small Is Beautiful Centralized system. Decentralization. Distributed system. Swarm intelligence. Network: peer-to-peer technology (e.g. Decentralized network 42). Monetary: Bitcoin. Animal communities: Red harvester ant.

Cloud computing

cloudcloud-basedcloud services
Peer-to-peer—A distributed architecture without the need for central coordination. Participants are both suppliers and consumers of resources (in contrast to the traditional client–server model). Green computing. Cloud sandbox—A live, isolated computer environment in which a program, code or file can run without affecting the application in which it runs. Agility for organizations may be improved, as cloud computing may increase users' flexibility with re-provisioning, adding, or expanding technological infrastructure resources. Cost reductions are claimed by cloud providers. A public-cloud delivery model converts capital expenditures (e.g., buying servers) to operational expenditure.

Sharing economy

sharingsharing economiescollaborative consumption
Increased independence, flexibility and self-reliance by decentralization, the abolition of monetary entry-barriers, and self-organization. Increased participatory democracy. Accelerating sustainable consumption and production patterns in cities around the globe. Increased quality of service through rating systems provided by companies involved in the sharing economy. Increased flexibility of work hours and wages for independent contractors of the sharing economy. Increased quality of service provided by incumbent firms that work to keep up with sharing firms like Uber and Lyft. Garden sharing. Heifer International. Seed swap. Crowd funding. Peer-to-peer banking. Peer-to-peer lending.

Anonymous P2P

anonymous peer-to-peeranonymousAnonymous peer to peer
Netsukuku - a peer-to-peer routing system aiming to build a free and independent Internet. Osiris (Serverless Portal System) - an anonymous and distributed web portals creator. Perfect Dark - a P2P client which relies on a mixnet and distributed datastore to provide anonymity (freeware, written for Windows). Syndie - a content (mainly forums) syndication program that operates over numerous anonymous and non-anonymous networks (open source, written in Java). Tribler - an open source anonymous peer-to-peer decentralized BitTorrent client. ZeroNet - a decentralized Internet-like network of peer-to-peer users. Allows tunneling of HTTP-traffic through Tor.

Ethereum Classic

Ethereum Classic (ETC)
Ethereum Classic is an open-source, public, blockchain-based distributed computing platform featuring smart contract (scripting) functionality. It provides a decentralized Turing-complete virtual machine, the Ethereum Virtual Machine (EVM), which can execute scripts using an international network of public nodes. Ethereum Classic and Ethereum have a value token called "ether", which can be transferred between participants, stored in a cryptocurrency wallet and is used to compensate participant nodes for computations performed in the Ethereum Platform. The classic ether token is traded on cryptocurrency exchanges under the ticker symbol ETC.

Decentralized application

decentralizeddecentralized applicationsdecentralized apps
A decentralized application (Dapp, dApp or DApp) is a computer application that runs on a distributed computing system. DApps have been mostly popularized by distributed ledger technologies (DLT), namely the Ethereum Blockchain, where DApps are often refereed to as smart contracts. The definition of a decentralized application is still in development and under debate. Typical definitions include the following attributes: There are three types of decentralized applications: Decentralized applications may run on top of other cryptographic systems such as Ethereum.

Decentralized autonomous organization

decentralized autonomous corporationblockchainDAO
The costs of a blockchain-enabled transaction and of the associated data reporting may be substantially offset by the elimination of both the trusted third party and of the need for repetitive recording of contract exchanges in different records. For example, the blockchain data could, in principle and if regulatory structures permit it, replace public documents such as deeds and titles. In theory, a blockchain approach allows multiple cloud computing users to enter a loosely coupled peer-to-peer smart contract collaboration.

Concurrent computing

concurrentconcurrent programmingconcurrency
[[List of important publications in concurrent, parallel, and distributed computing]]. Ptolemy Project. Sheaf (mathematics). Software transactional memory. Transaction processing.