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.
GameCoin (GMC) is a digital currency targeted towards the gaming community. GMC tokens go on sale at the end of September through the GameCoin ICO. GameCoin aims to increase the revenue of the gaming industry by 3 times – or 300 billion dollars per year. It aims to allow players to earn money from their hobby. And, within a year, the developers claim the capitalization of GameCoin will “exceed and billion dollars and will continue to grow rapidly.” GameCoin is being proposed as a way to monetize the world of free gaming. The GameCoin whitepaper explains that the majority of gaming revenue comes from 10% of users. Today, developers are struggling to monetize the remaining 90% of users. GameCoin claims to have found a way to do that using blockchain technology. Basically, GameCoin’s idea is to allow each game developer to create their own cryptocurrency. This cryptocurrency is used as in-game money. The developers can create this cryptocurrency at virtually no cost to themselves – it’s just a digital token that has value in the game. However, by the time it circulates through gamers, the token will have value because it can be used to pay for in-game items. In more straightforward terms, GameCoin plans to make it easy for developers to create a secure in-game currency. It appears that these cryptocurrencies will operate as forks on the GameCoin blockchain. Each developer will be able to make their own fork – so gamers can easily apply their GWC tokens to any game of their choice (the GameCoin wallet will support all forks).