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.
Dai is a stablecoin. It is an Ethereum ERC20 token that is pegged to $1 USD — every Dai is worth $1, and will always be worth $1, regardless of how much Dai is in existence. There is no centralized authority like Tether that backs its value, and no traditional bank that backs each Dai with a real US dollar. There is nothing that can be shut down, and no centralized authority that needs to be trusted. Dai lives entirely within the Ethereum blockchain using smart contracts. *Features of Dai: 1. Dai is always worth $1 USD each 2. It can be freely traded like any other ERC20 token 3. Anyone with an Ethereum wallet can own, accept, and transfer it 4. It can be exchanged without any middleman 5. No individual person or company has control over it 6. No government or authority can shut it down *How Dai Works? Dai is a masterpiece of game theory that carefully balances economic incentives in the pursuit of one goal — a token that is continuously approaching the value of $1 USD. When Dai is worth above $1, mechanisms work to decrease the price. When Dai is worth below $1, mechanisms work to increase the price. The rational actors that take part in these mechanisms do so because they earn money anytime Dai is not perfectly worth $1. This is why Dai is always floating slightly above or below $1 — it is an endless wave function bouncing infinitely close to $1, but never quite achieving it. The farther Dai goes from $1, the more incentive there is to fix it. This is the magic of Dai. *How is Dai Created? Dai is simply a loan against Ethereum. By using the MakerDAO dApp, advanced users can take loans out in Dai against their ETH holdings. First, ETH is turned into “wrapped ETH” (WETH), which is simply an ERC20 wrapping around ETH. This “tokenizes” ETH so it can be used like any other ERC20 token. Next, WETH is turned into “pooled ETH” (PETH), which means it joins a large pool of Ethereum that is the collateral for all Dai created. Once you have PETH, you can create a “collateralized debt position” (CDP), which locks up your PETH and allows you to draw Dai against your collateral, which is PETH. As you draw out Dai, the ratio of debt in the CDP increases. There is a debt limit that sets a maximum amount of Dai you can draw against your CDP. Once you have Dai, you can spend or trade it freely like any other ERC20 token. *There are several important reasons why you would create Dai, despite the hassle: 1. You need a loan, and have an asset (ETH) to use as collateral for your loan 2. You believe ETH is going up in value. You can use your CDP to buy ETH on margin — you lock up your ETH in a CDP, draw Dai against it, use the Dai to buy more ETH on an exchange, and then use that ETH to further increase the size of your CDP. This can be accomplished without any third-party or centralized authority allowing you to do so — margin trading can be accomplished entirely on the blockchain. 3. The demand for Dai has driven the price above $1 USD. When this occurs, you can create Dai then immediately sell it on an exchange for greater than $1 USD. This is essentially free money, and is one of the mechanisms the Maker system uses to keep Dai pegged to $1 USD. Dai being worth over $1 USD encourages more Dai to be created. These three reasons are enough to ensure that Dai is continually created.