The bitcoin network is a peer-to-peer payment network that operates on a cryptographic protocol. Users send and receive bitcoins, the units of currency, by broadcasting digitally signed messages to the network using bitcoin cryptocurrency wallet software. Transactions are recorded into a distributed, replicated public database known as the blockchain, with consensus achieved by a proof-of-work system called mining. Satoshi Nakamoto, the designer of bitcoin claimed that design and coding of bitcoin began in 2007. The project was released in 2009 as open source software. The network requires the minimal structure to share transactions. An ad hoc decentralized network of volunteers is sufficient. Messages are broadcast on a best effort basis, and nodes can leave and rejoin the network at will. Upon reconnection, a node downloads and verifies new blocks from other nodes to complete its local copy of the blockchain. A bitcoin is defined by a sequence of digitally signed transactions that began with the bitcoin's creation, as a block reward. The owner of a bitcoin transfers it by digitally signing it over to the next owner using a bitcoin transaction, much like endorsing a traditional bank check. A payee can examine each previous transaction to verify the chain of ownership. Unlike traditional check endorsements, bitcoin transactions are irreversible, which eliminates the risk of chargeback fraud. Although it is possible to handle bitcoins individually, it would be unwieldy to require a separate transaction for every bitcoin in a transaction. Transactions are therefore allowed to contain multiple inputs and outputs, allowing bitcoins to be split and combined. Common transactions will have either a single input from a larger previous transaction or multiple inputs combining smaller amounts, and one or two outputs: one for the payment, and one returning the change, if any, to the sender. Any difference between the total input and output amounts of a transaction goes to miners as a transaction fee. In 2013, Mark Gimein estimated electricity consumption to be about 40.9 megawatts (982 megawatt-hours a day). In 2014, Hass McCook estimated 80.7 megawatts (80,666 kW). As of 2015, The Economist estimated that even if all miners used modern facilities, the combined electricity consumption would be 166.7 megawatts (1.46 terawatt-hours per year). To lower the costs, bitcoin miners have set up in places like Iceland where geothermal energy is cheap and cooling Arctic air is free. Chinese bitcoin miners are known to use hydroelectric power in Tibet to reduce electricity costs. Various potential attacks on the bitcoin network and its use as a payment system, real or theoretical, have been considered. The bitcoin protocol includes several features that protect it against some of those attacks, such as unauthorized spending, double spending, forging bitcoins, and tampering with the blockchain. Other attacks, such as theft of private keys, require due care by users.
Namecoin is a domain name registry service and was the first coin to fork Bitcoin. Similar to registering a .com or .io domain name, you register a .bit domain on the network. This domain is censorship-resistant and impervious to activity tracking. Governments and large corporations control traditional domain name services (DNS) servers. This control is how the Chinese government, for instance, can block websites that go against their beliefs. To prevent this level of censorship, Namecoin uses blockchain technology to distribute its DNS amongst the users on the network. A pseudo-anonymous founder by the name of “Vince” created Namecoin in 2011. Since then, Vince has disappeared, but a core development team has kept the project alive. The project has several developers listed on the official website and benefits from the contributions of numerous anonymous developers as well. Namecoin has been fully functional for a few years, now, and the development team posts updates several times a month. Namecoin was the first cryptocurrency to use Auxiliary Proof of Work (AuxPoW) for its consensus. By using AuxPow, Namecoin and Bitcoin can be mined simultaneously. In this consensus, the child blockchain depends on the proof-of-work of parent blockchain, which means If a new block is created on Bitcoin blockchain, it will also be added to the Namecoin blockchain. NameID is another technology brought by Namecoin. It serves as an open service for securely registering human-readable names in a decentralized way. NameID is a combination between Namecoin and OpenId, where users can easily convert their Namecoin Identities into OpenIDs. This makes NameID a solution to Zooko's triangle, which states that there are three desirable properties (Human-meaningful, Decentralized, and Secure) for name participants in a network protocol and any participant can only inherit two properties at a given time. Namecoin is among some earliest cryptocurrencies. During its existence in the market, it has seen a high volatility on some occasions, which can be attributed to many reasons. Namecoin has been around in the cryptocurrency market much longer than most cryptocurrencies today; however, despite this, it has not gotten much attention until recently. In 2014, it was among the top ten cryptocurrencies by market capitalisation, which is now changed due to the introduction of hundreds of new cryptocurrencies. Namecoin was abandoned by its creator which can be seen as a red flag by many. The project is currently being developed with the support from its community. The current team has been actively taking the project forward and also provides regular updates on social media channels.