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Ethereum: basics 1

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Download Ethereum Blockchain - Epoch 12

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Basics: Epoch 12: The Block Header

Block Header in details

As we already explained in Basics: The block, the block is a very important part of the block chain.
Here we present a detailed list extracted from the Ethereum yellow paper

  • parentHash: the hash of the parent block's header
  • ommersHash: the hash of the ommers header
  • beneficiary: the address of the miner of this block
  • difficulty: the difficulty level of the block (calculated from previous block difficulty and timestamp)
  • number: the number of ancestors (genesis has 0)
  • gasLimit: the gas limit for this block
  • gasUsed: the sum of gas spent for every transaction in this block
  • timestamp: the timestamp (Unix time) of this block's inception
  • stateRoot: the hash of the root node of state trie (after transactions execution)
  • transactionsRoot: the hash of the root node of all transactions in the node
  • receiptsRoot: the hash of the root node of all receipts of every transaction
  • logsBloom: a Bloom filter of receipt logs
  • extraData: extra info of this block (max 32 bytes), usually who mined the block inserts its own informations
  • mixHash: in combination with nonce, proves that a sufficient amount of computation has been done
  • nonce: in combination with mixHash, proves that a sufficient amount of computation has been done
So when you make a transaction you need to have the ether to cover the gas cost in your account.
To avoid losing all your money, you can set the gas limit.
If you don't have sufficient gas to run your transaction, at some point the process aborts and the transaction is rolled back.
But in this case, a part of the gas has been spent, so your ether balance will be decreased.
If you want to test all these things you can set your own test network, but this requires little bit advanced skills, and we will explain how to do it in the future.

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