Bitcoin mining is the process of adding transaction records to Bitcoin’s public ledger of past transactions or blockchain. This ledger of past transactions is called the block chain as it is a chain of blocks. The block chain serves to confirm transactions to the rest of the network as having taken place.
Bitcoin nodes use the block chain to distinguish legitimate Bitcoin transactions from attempts to re-spend coins that have already been spent elsewhere.
What is Bitcoin Mining?
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What is the Blockchain?
Bitcoin mining is intentionally designed to be resource-intensive and difficult so that the number of blocks found each day by miners remains steady. Individual blocks must contain a proof of work to be considered valid. This proof of work is verified by other Bitcoin nodes each time they receive a block. Bitcoin uses the hashcash proof-of-work function.
The primary purpose of mining is to allow Bitcoin nodes to reach a secure, tamper-resistant consensus. Mining is also the mechanism used to introduce Bitcoins into the system: Miners are paid any transaction fees as well as a “subsidy” of newly created coins.
This both serves the purpose of disseminating new coins in a decentralized manner as well as motivating people to provide security for the system.
Bitcoin mining is so called because it resembles the mining of other commodities: it requires exertion and it slowly makes new currency available at a rate that resembles the rate at which commodities like gold are mined from the ground.
What is Proof of Work?
A proof of work is a piece of data which was difficult (costly, time-consuming) to produce so as to satisfy certain requirements. It must be trivial to check whether data satisfies said requirements.
Producing a proof of work can be a random process with low probability, so that a lot of trial and error is required on average before a valid proof of work is generated. Bitcoin uses the Hashcash proof of work.
What is Bitcoin Mining Difficulty?
The Computationally-Difficult Problem
Bitcoin mining a block is difficult because the SHA-256 hash of a block’s header must be lower than or equal to the target in order for the block to be accepted by the network.
This problem can be simplified for explanation purposes: The hash of a block must start with a certain number of zeros. The probability of calculating a hash that starts with many zeros is very low, therefore many attempts must be made. In order to generate a new hash each round, a nonce is incremented. See Proof of work for more information.
The Bitcoin Network Difficulty Metric
The Bitcoin mining network difficulty is the measure of how difficult it is to find a new block compared to the easiest it can ever be. It is recalculated every 2016 blocks to a value such that the previous 2016 blocks would have been generated in exactly two weeks had everyone been mining at this difficulty. This will yield, on average, one block every ten minutes.
As more miners join, the rate of block creation will go up. As the rate of block generation goes up, the difficulty rises to compensate which will push the rate of block creation back down. Any blocks released by malicious miners that do not meet the required difficulty target will simply be rejected by everyone on the network and thus will be worthless.
The Block Reward
When a block is discovered, the discoverer may award themselves a certain number of bitcoins, which is agreed-upon by everyone in the network. Currently this bounty is 25 bitcoins; this value will halve every 210,000 blocks. See Controlled Currency Supply.
Additionally, the miner is awarded the fees paid by users sending transactions. The fee is an incentive for the miner to include the transaction in their block. In the future, as the number of new bitcoins miners are allowed to create in each block dwindles, the fees will make up a much more important percentage of mining income.
What is ‘Bitcoin Mining’
Bitcoin mining is the process by which transactions are verified and added to the public ledger, known as the block chain, and also the means through which new bitcoin are released. Anyone with access to the internet and suitable hardware can participate in mining. The mining process involves compiling recent transactions into blocks and trying to solve a computationally difficult puzzle. The participant who first solves the puzzle gets to place the next block on the block chain and claim the rewards. The rewards, which incentivize mining, are both the transaction fees associated with the transactions compiled in the block as well as newly released bitcoin. (Related: How Does Bitcoin Mining Work?)
BREAKING DOWN ‘Bitcoin Mining’
The amount of new bitcoin released with each mined block is called the block reward. The block reward is halved every 210,000 blocks, or roughly every 4 years. The block reward started at 50 in 2009, is now 25 in 2014, and will continue to decrease. This diminishing block reward will result in a total release of bitcoin that approaches 21 million.
How hard are the puzzles involved in mining? Well, that depends on how much effort is being put into mining across the network. The difficulty of the mining can be adjusted, and is adjusted by the protocol every 2016 blocks, or roughly every 2 weeks. The difficulty adjusts itself with the aim of keeping the rate of block discovery constant. Thus if more computational power is employed in mining, then the difficulty will adjust upwards to make mining harder. And if computational power is taken off of the network, the opposite happens. The difficulty adjusts downward to make mining easier.
In the earliest days of Bitcoin, mining was done with CPUs from normal desktop computers. Graphics cards, or graphics processing units (GPUs), are more effective at mining than CPUs and as Bitcoin gained popularity, GPUs became dominant. Eventually, hardware known as an ASIC, which stands for Application-Specific Integrated Circuit, was designed specifically for mining bitcoin. The first ones were released in 2013 and have been improved upon since, with more efficient designs coming to market. Mining is competitive and today can only be done profitably with the latest ASICs. When using CPUs, GPUs, or even the older ASICs, the cost of energy consumption is greater than the revenue generated.
Blocks are files where data pertaining to the Bitcoin network is permanently recorded. A block records some or all of the most recent Bitcoin transactions that have not yet entered any prior blocks. Thus a block is like a page of a ledger or record book. Each time a block is ‘completed’, it gives way to the next block in the blockchain. A block is thus a permanent store of records which, once written, cannot be altered or removed.
BREAKING DOWN ‘Block (Bitcoin Block)’
The Bitcoin network witnesses a great deal of transaction activity. Maintaining a record of these transactions helps users track what was paid to and by whom. The transactions executed during a given period of time are recorded into a file called a block.
By way of analogy, let’s compare ordinary banking transactions to transactions over the Bitcoin network. A blockchain is like a record of bank transactions whereas a block might be a single transaction confirmation that a bank ATM prints out after you use the machine. In other words, the relationship of block to blockchain is one of part to whole.
A block represents the ‘present’ and contains information about its past and future. Each time a block is completed it becomes part of the past and gives way to a new block in the blockchain. The completed block is a permanent record of transactions in the past and the new transactions are recorded in the current one. This way the whole system works in a cycle and data gets permanently stored. Each block comprises records of some or all recent transactions, and a reference to the block that preceded it.
A mathematical problem is linked with each block. Miners are constantly processing and recording transactions as part of the process of competing in a type of race. They race to ‘complete the current block’ in order to win Bitcoins. When a winning miner is able to solve it, the answer is shared with other mining nodes and it is validated. Every time a miner solves a problem, a newly minted 12.5 BTC (Bitcoin currency symbol) is awarded to the miner and enters the circulation. The first record in that next block is a transaction that awards the winning miner (who completed the previous block) the newly minted BTC. It is the difficulty of the mathematical problem that regulates the creation rate of new Bitcoins since new blocks can’t be submitted to the network without the answer. Based on the fact that it takes around 10 minutes on an average to solve the problem, approximately 12.5 new Bitcoins are minted every 10 minutes.
BREAKING DOWN ‘Bitcoin Cash’
Since its launch, Bitcoin faced pressure from community members on the topic of scalability. Specifically, that the size of blocks – set at 1 megabyte (MB), or a million bytes, in 2010 – would slow down transaction processing times, thus limiting the currency’s potential, just as it was gaining in popularity. The block size limit was added to the Bitcoin code in order to prevent spam attacks on the network at a time when the value of a Bitcoins was low. By 2015, the value of Bitcoins had increased substantially and average block size had reached 600 bytes, creating a scenario in which transaction times could run into delays as more blocks reached maximum capacity.
A number of proposals have been made to deal with transaction processing over the years, often focusing on increasing block size. Because the Bitcoin code is not managed by a central authority, changes to the code require buy-in from developers and miners. This consensus-driven approach can lead to proposals taking a long time to finalize. This has resulted in groups creating separate blockchain ledgers using new standards, called a fork. Several forks, such as Bitcoin XT and Bitcoin Unlimited, failed to be adopted by a wide audience. Bitcoin Cash, launched in August 2017, is another fork from Bitcoin Classic.
Bitcoin Cash differs from Bitcoin Classic in that it increases the block size from 1 MB to 8 MB. It also removes Segregated Witness (SegWit), a proposed code adjustment designed to free up block space by removing certain parts of the transaction. The goal of Bitcoin Cash is to increase the number of transactions that can be processed, and supporters hope that this change will allow Bitcoin Cash to compete with the volume of transactions that PayPal and Visa can handle by increasing the size of blocks.
Because the computer power required to process larger blocks could price out some smaller miners, critics worry that adopting Bitcoin Cash’s approach will lead to power being concentrated in the hands of companies that can afford more and better equipment. Opponents to the fork worry that this will threaten the consensus-driven approach to Bitcoin, as a small number of companies could control Bitcoin and more readily force changes on the community in the future.
A successful hard fork for Bitcoin Cash entails surviving long enough to entice individuals and companies to use and mine the new digital currency if it is able to build substantial interest and reach critical mass. Once this point is reached, however, Bitcoin Cash may find that its success has prompted others to develop their own alternative coins, which would put the same pressure on Bitcoin Cash that it had placed on Bitcoin Classic. Since the issue of scalability tends to be at the forefront of cryptocurrency debates, developers have made increasing block size and improving transaction processing speeds their top focus areas.
The Genesis Block is the first-ever block of Bitcoin mined by creator Satoshi Nakamoto. The original block has 50 bitcoins in it and was mined over the course of six days in 2009. The 50 bitcoins within the block are unspendable, however, and it’s a subject of much debate whether this was intentional or a fluke on Nakamoto’s part. Also known as Block 0.
BREAKING DOWN ‘Genesis Block’
When Satoshi Nakamoto began mining the Genesis Block on January 3rd, 2009, it’s possible that he (or she or a group of people) had any clue about the chain of events it would set off.
The Genesis Block, also known as Block 0, is the ancestor that every other block in the chain can trace its lineage back to. It was mined over the course of six days by Nakamoto, which is puzzling to Bitcoin fans, as the average timestamp gap between mining blocks is normally just ten minutes. So why did this first block take so long? The most logical explanation is that Nakamoto was testing his creation to make sure the original block was perfect. It had to be, since it would be hardwired into the system forever.
The Genesis Block’s Secret Message
Perhaps the most mystifying aspect of the Genesis Block is the secret message that Nakamoto imbued within the Block’s raw data.
“The Times 03/Jan/2009 Chancellor on brink of second bailout for banks”
While Nakamoto never commented on the meaning of his message, it’s not hard to infer that it serves as a mission statement for Bitcoin itself. The text comes from a headline in the January 3rd, 2009 edition of The Times, a London-based newspaper. The article reported on the British government’s failing to stimulate the economy following the 2008 financial crisis.
Nakamoto famously hated the idea of too-big-to-fail institutions and intended Bitcoin to be different. Bitcoin couldn’t be bailed out because there was no corporation or middleman between the currency and the consumer. Looking at all of this, it seems pretty likely that Nakamoto’s reference to the article was a hint as to why he chose that moment for Bitcoin to be born.
Interestingly, the 50 bitcoin reward contained within the Genesis Block is unable to be spent due to a minor change in the code. It’s unknown whether this was intentional or unintentional on Nakamoto’s part. People have been donating small amounts of Bitcoin in tribute to Nakamoto by transferring funds to this original block. This is seen as a kind of sacrifice, since once a coin is moved into the Genesis Block, it cannot be moved, sort of like throwing a quarter into a fountain.
The Genesis Block is the backbone of the entire bitcoin system, and the origin of Bitcoin itself. If every transaction with Bitcoin were like a fork in the road, then all those roads would eventually lead back to the Genesis Block.