I know how mining works and how transactions are added to the blockchain. What I don't understand is the association between the two...if any.

I've read a few times about how a cryptocurrency transaction is added to the blockchain through consensus. This often means PoW. Then there is mentioned that miners perform PoW and the transactions are cleared. How?

Miners mine for coins right? What does mining have to do with verifying unrelated transactions?

At least for bitcoin, is it even possible for miners to keep up with all of the transactions occurring?

1 Answer 1


How users / nodes see it:

When transactions are made, they stay in nodes' memory pools ("mempool") until a block that contains them, becomes mined and relayed. When this happens, that transactions become a permanent member of the blockchain (unless that block is orphaned).

How miners see it:

Miners' major incentives are block rewards. However, to maximize their profit, they can also include transactions in their block (According to BlockChair, 124k of 510k blocks include no transaction.) If they include transactions in their block, they'll be able to collect their transaction fees. That's why most of the blocks include transactions (and the miners who don't include transactions are mostly illogical).

tl;dr When miners include your transactions, your transactions become a permanent element of the blockchain. They do this to collect your transactions' fees, to maximize their profit.

  • Using bitcoin as an example, are you saying that when miners mine for bitcoin, each mined coin creates a block on the blockchain as a byproduct? How is that viable with bitcoin given the large number of transactions and then amount of time it takes to mine a coin? Seems as though miners can't mine enough to create new blocks for all of the transactions.
    – 4thSpace
    Commented Feb 17, 2018 at 16:55
  • 1
    @4thSpace No, they mine for blocks and new coins are the product. And adding transactions to your block doesn't affect your luck finding a block. BTC miners can't put all of the transactions in their mempool, because there is a 1 MB (actually 4 MB with SegWit) limit of transactions you can put into your block. Miners put the transactions with the most fee/kb to their blocks, to maximize their profits.
    – MCCCS
    Commented Feb 17, 2018 at 18:00
  • Do you have a reference to discusses miners mine for blocks? First time I've heard of that. Everything I've read so far says they mine for coins, not blocks.
    – 4thSpace
    Commented Feb 18, 2018 at 16:19
  • @4thSpace There has been 2 blocks, which their block reward was not claimed; however, there can't be any newly created coins without a block. Of course, miners absolutely mine for coins, and I was trying to say that coins are the product of block, not vice versa.
    – MCCCS
    Commented Feb 19, 2018 at 4:17

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