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.
Tezos is a coin created by a former Morgan Stanley analyst, Arthur Breitman. It is a smart contract platform which is does not involve in mining Tezos coins. It is a coin that promotes themselves on major ideas of self-amendment and on-chain governance. It is an Ethereum-like blockchain that hosts smart contracts. It allows the community to vote and improve its flaws. Any token holder may delegate their voting rights to others in the network. The coin uses a generic network shell which allow different transaction and consensus protocols that a blockchain needs to be compatible. The source code is implemented on OCaml which is a fast, flexible and functional programming language which should suit an ambitious project and its technical requirements. Tezos’ proof-of-stake consensus algorithm is different from the delegated proof-of-stake (dPOS) where they go by the name liquid proof-of-stake. This liquid proof-of-stake that Tezos uses focus in filling the gap between both security and decentralization but still being able to take advantage of the benefits that delegated proof-of-stake offers. The staking process in Tezos is called “baking”. In this blockchain, bakers who make deposits will be rewarded for signing up and publishing blocks. However, if a baker commits any bad behavior the deposits will be forfeited. Baking & Endorsing Baking is what Tezos refers to as the action of signing and publishing a new block in the chain. Bakers need at least 10,000 XTZ to qualify as a delegate, and having additional delegated stake increases their chances of being selected as a Baker or Endorser. At the beginning of each cycle (4096 blocks), the Bakers for each block are randomly selected and published. Bakers earn a block reward of 16 XTZ for baking a block. In addition to the Baker, 32 Endorsers are randomly selected to verify the last block that was baked. Endorsers receive 2 XTZ for each block they endorse. Block Rewards & Inflation Block rewards are funded by protocol defined inflation. Rewards are calibrated so that the number of XTZ tokens grows at roughly 5.5% per year. If 100% of Tezos tokens are delegated, the annualized yield will be 5.5%. Currently, 38% of Tezos tokens have been delegated, including the 10% owned by the Tezos Foundation, so the annualized yield is currently 14%. To ensure Bakers and Endorsers act honestly, they are required to post a security deposit for each block they Bake or Endorse. They forfeit this deposit in the event of malicious activity, such as double baking or double endorsing a block. In 2018, Tezos successfully launched their main network after delaying the launch due to corporate governance disputes. The Tezos foundation planned to transition the network to a mainnet, or a more complete version. The foundation has also raised $232 million in July 2017 to build the network and issue a new type of cryptocurrency to its backers in one of the largest- ever initial coin offerings. The founders have also made it clear in their blog that the network is using a new blockchain technology hence unexpected issues may still occur affecting the network. Check out CoinBureau for the complete review of Tezos.