6

Miners pick transactions from the mempool which is the queue of unconfirmed transactions. When there are fewer transactions waiting than would fit into a block, the block will not be full. The miner could create more transactions themselves, but that would be only useful if they wanted to send one themselves already in the first place, otherwise they'd just ...


4

The process of a transaction being created and included in the blockchain is as follows: The sender creates, signs, and broadcasts the transaction All Bitcoin full nodes, including miners and regular users, receive the transaction and validate it by making sure it follows the Bitcoin protocol rules Nodes temporarily store the unconfirmed/yet-to-be-mined ...


3

Historically it was not required to include a fee for every transaction. A large portion of miners would mine transactions with no fee given that they had enough "priority". Today, low priority is mostly used as an indicator for spam transactions and almost all miners expect every transaction to include a fee. Today miners choose which transactions to mine ...


2

Priority was calculated based on the age of the inputs. Older and larger inputs were given a higher priority than new and low valued inputs. This allowed transactions to pay no transaction fees but still be included blocks. So what used to happen is that 50 kB of a block was reserved for transactions that paid no fees. Transactions were selected for ...


2

When a miner validates a block, does the block contain all transactions in Bitcoin for that time period? See this question for info about the structure of a block. A block can contain up to 4,000,000 weight units worth of transactions. So the miner can select transactions to include in the block, up to this limit. Generally, the miner will select the ...


2

While miners do try to maximize transaction space, they can't always fill a block. Miners usually start with a block template that contains just the coinbase transaction - that alone will net them the block reward, currently 12.5 BTC. Any transaction fees over and above that are "free" money. When blocks are mined in quick succession, it may take miners a ...


2

For miners lower transaction fee doesn't matters but fee rate does. There are three cases where the miner chooses transactions with low fee rates. 1) When the mempool has three sets of transactions {A}:High fee rate , {B}:Average fee rate and {C}:Low fee rate. If there are few transactions of set A and B the miner will select transactions from C as well. 2)...


1

I assume the worst-case scenario, wherein the mempool there are many high fee tx and many low tx to choose from. Low fee tx may take a longer time to confirm. Miners don't have to worry that this tx gets included in other miners' block. This may give a slower miner some advantages in terms of mining. The miner may have taken some extra time to pre-calculate ...


1

Miners do optimize the block construction process internally. Unfortunately they do not share this information with the community, so we don't know what methods they use, how they choose TX's and how they distribute work to pool participants. Both mining machines and mining software the big miners use are secret. Modern ASIC machines' hardware are closed ...


1

Nodes will relay all transactions to each other, true. But, how do you know all miners have the same block if only one is actually published? In any case, miners are incentivized monetarily to include the transactions with the highest fee rate (fee/kB) because the miner gets all of the transaction fees. So, it would not be surprising if miners had similar ...


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