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.


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.


torrentBitTorrent protocoltorrents
Florida State University uses BitTorrent to distribute large scientific data sets to its researchers. Many universities that have BOINC distributed computing projects have used the BitTorrent functionality of the client-server system to reduce the bandwidth costs of distributing the client-side applications used to process the scientific data. The developing Human Connectome Project uses BitTorrent to share their open dataset. Facebook uses BitTorrent to distribute updates to Facebook servers. Twitter uses BitTorrent to distribute updates to Twitter servers.

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.

Consensus (computer science)

consensusconsensus problemsdistributed consensus
Nodes in the bitcoin network attempt to solve a cryptographic proof-of-work problem, where probability of finding the solution is proportional to the computational effort, in hashes per second, expended, and the node that solves the problem has their version of the block of transactions added to the peer-to-peer distributed timestamp server accepted by all of the other nodes. As any node in the network can attempt to solve the proof-of-work problem, a Sybil attack becomes unfeasible unless the attacker has over 50% of the computational resources of the 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.

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.

Distributed networking

Distributed Network
Peer-to-peer (P2P) computation is based on a decentralized, distributed network, including the distributed ledger technology blockchain. Mesh networking is a local network composed of devices (nodes) that communicate through radio waves, allowing for different types of devices. Each node communicates with every other node on the network. Prior to the 1980's, computing was typically centralized on a single low-cost desktop computer. But today, computing resources (computers or servers) are typically physically distributed in many places, which distributed networking excels at.

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.

Computer cluster

It is distinct from other approaches such as peer to peer or grid computing which also use many nodes, but with a far more distributed nature. A computer cluster may be a simple two-node system which just connects two personal computers, or may be a very fast supercomputer. A basic approach to building a cluster is that of a Beowulf cluster which may be built with a few personal computers to produce a cost-effective alternative to traditional high performance computing. An early project that showed the viability of the concept was the 133-node Stone Soupercomputer.


e-mailelectronic maile-mails
For example, Virtual Private Networks or the Tor anonymity network can be used to encrypt traffic from the user machine to a safer network while GPG, PGP, SMEmail, or S/MIME can be used for end-to-end message encryption, and SMTP STARTTLS or SMTP over Transport Layer Security/Secure Sockets Layer can be used to encrypt communications for a single mail hop between the SMTP client and the SMTP server. Additionally, many mail user agents do not protect logins and passwords, making them easy to intercept by an attacker. Encrypted authentication schemes such as SASL prevent this. Finally, attached files share many of the same hazards as those found in peer-to-peer filesharing.


C++ programming languageC++ standardC++ language
C++ has also been found useful in many other contexts, with key strengths being software infrastructure and resource-constrained applications, including desktop applications, servers (e.g. e-commerce, Web search or SQL servers), and performance-critical applications (e.g. telephone switches or space probes). C++ is a compiled language, with implementations of it available on many platforms. Many vendors provide C++ compilers, including the Free Software Foundation, Microsoft, Intel, and IBM.

Clustered file system

distributed file systemnetwork file systemshared disk file system
Peer-to-peer file sharing. Disk sharing. Distributed data store. Distributed file system for cloud. Global file system. Gopher (protocol). List of distributed file systems. CacheFS. RAID. A Taxonomy of Distributed Storage Systems. A Taxonomy and Survey on Distributed File Systems. A survey of distributed file systems. The Evolution of File Systems.

World Wide Web

Webthe webweb-based
The hostname of a web server is often www, in the same way that it may be ftp for an FTP server, and news or nntp for a Usenet news server. These host names appear as Domain Name System (DNS) or subdomain names, as in The use of www is not required by any technical or policy standard and many web sites do not use it; the first web server was

Local area network

LANlocal networklocal
These then formed the basis for collaboration between Microsoft and 3Com to create a simple network operating system LAN Manager and its cousin, IBM's LAN Server. None of these enjoyed any lasting success. In 1983, TCP/IP was first shown capable of supporting actual defense department applications on a Defense Communication Agency LAN test bed located at Reston, Virginia. The TCP/IP-based LAN successfully supported Telnet, FTP, and a Defense Department teleconferencing application. This demonstrated the feasibility of employing TCP/IP LANs to interconnect Worldwide Military Command and Control System (WWMCCS) computers at command centers throughout the United States.

EDonkey network

eDonkeyeD2keDonkey2000 network
The eDonkey Network (also known as the eDonkey2000 network or eD2k) is a decentralized, mostly server-based, peer-to-peer file sharing network created in 2000 by US developers Jed McCaleb and Sam Yagan that is best suited to share big files among users, and to provide long term availability of files. Like most sharing networks, it is decentralized, as there is not any central hub for the network; also, files are not stored on a central server but are exchanged directly between users based on the peer-to-peer principle. The server part of the network is proprietary freeware.