Numbered bitcoin minerals
Consequently, the time the last Bitcoin will be created will also vary, and is subject to speculation based on assumptions. If the mining power had remained constant since the first Bitcoin was mined, the last Bitcoin would have been mined somewhere near October 8th, Due to the mining power having increased overall over time, as of block , - assuming mining power remained constant from that block forward - the last Bitcoin will be mined on May 7th, As it is very difficult to predict how mining power will evolve into the future - i.
The total number of bitcoins, as mentioned earlier, has an asymptote at 21 million, due to a side-effect of the data structure of the blockchain - specifically the integer storage type of the transaction output , this exact value would have been 20,, Should this technical limitation be adjusted by increasing the size of the field, the total number will still only approach a maximum of 21 million.
The number of bitcoins are presented in a floating point format. However, these values are based on the number of satoshi per block originally in integer format to prevent compounding error. Therefore, all calculations from this block onwards must now, to be accurate, include this underpay in total Bitcoins in existence.
Then, in an act of sheer stupidity, a more recent miner who failed to implement RSK properly destroyed an entire block reward of The bitcoin inflation rate steadily trends downwards.
The block reward given to miners is made up of newly-created bitcoins plus transaction fees. As inflation goes to zero miners will obtain an income only from transaction fees which will provide an incentive to keep mining to make transactions irreversible. Due to deep technical reasons, block space is a scarce commodity , getting a transaction mined can be seen as purchasing a portion of it.
By analogy, on average every 10 minutes a fixed amount of land is created and no more, people wanting to make transactions bid for parcels of this land. The sale of this land is what supports the miners even in a zero-inflation regime. The price of this land is set by demand for transactions because the supply is fixed and known and the mining difficulty readjusts around this to keep the average interval at 10 minutes.
The theoretical total number of bitcoins, slightly less than 21 million, should not be confused with the total spendable supply. The total spendable supply is always lower than the theoretical total supply, and is subject to accidental loss, willful destruction, and technical peculiarities. One way to see a part of the destruction of coin is by collecting a sum of all unspent transaction outputs, using a Bitcoin RPC command gettxoutsetinfo. Note however that this does not take into account outputs that are exceedingly unlikely to be spent as is the case in loss and destruction via constructed addresses, for example.
The algorithm which decides whether a block is valid only checks to verify whether the total amount of the reward exceeds the reward plus available fees. Therefore it is possible for a miner to deliberately choose to underpay himself by any value: This is a form of underpay which the reference implementation recognises as impossible to spend.
Some of the other types below are not recognised as officially destroying Bitcoins; it is possible for example to spend the 1BitcoinEaterAddressDontSendf59kuE if a corresponding private key is used although this would imply that Bitcoin has been broken.
Bitcoins may be lost if the conditions required to spend them are no longer known. For example, if you made a transaction to an address that requires a private key in order to spend those bitcoins further, had written that private key down on a piece of paper, but that piece of paper was lost.
In this case, that bitcoin may also be considered lost, as the odds of randomly finding a matching private key are such that it is generally considered impossible. Bitcoins may also be willfully 'destroyed' - for example by attaching conditions that make it impossible to spend them. A common method is to send bitcoin to an address that was constructed and only made to pass validity checks, but for which no private key is actually known.
An example of such an address is "1BitcoinEaterAddressDontSendf59kuE", where the last "f59kuE" is text to make the preceding constructed text pass validation. Finding a matching private key is, again, generally considered impossible.
For an example of how difficult this would be, see Vanitygen. Another common method is to send bitcoin in a transaction where the conditions for spending are not just unfathomably unlikely, but literally impossible to meet. A lesser known method is to send bitcoin to an address based on private key that is outside the range of valid ECDSA private keys. The first BTC 50, included in the genesis block , cannot be spent as its transaction is not in the global database.
Bitcoin uses the hashcash proof-of-work function. The primary purpose of mining is to set the history of transactions in a way that is computationally impractical to modify by any one entity. By downloading and verifying the blockchain, bitcoin nodes are able to reach consensus about the ordering of events in bitcoin.
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: An important difference is that the supply does not depend on the amount of mining.
In general changing total miner hashpower does not change how many bitcoins are created over the long term. Mining a block is difficult because the SHA 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 difficulty is the measure of how difficult it is to find a new block compared to the easiest it can ever be. The rate is recalculated every 2, blocks to a value such that the previous 2, blocks would have been generated in exactly one fortnight two weeks had everyone been mining at this difficulty.
This is expected yield, on average, one block every ten minutes. As more miners join, the rate of block creation increases. As the rate of block generation increases, the difficulty rises to compensate, which has a balancing of effect due to reducing the rate of block-creation. Any blocks released by malicious miners that do not meet the required difficulty target will simply be rejected by the other participants in the network.
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 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.
Users have used various types of hardware over time to mine blocks. Hardware specifications and performance statistics are detailed on the Mining Hardware Comparison page.