A block is one unit of a BlockchainBlockchainA public ledger where transactions are grouped into blocks, each linked to the one before, so past records can't be altered without it showing.: a batch of transactionsTransactionA record of crypto moving from one wallet address to another, signed with the sender's private key and stored permanently on the blockchain. added to the chain in one go. Think of a block as one page in a ledger book. When the page is full and approved, it goes to the back of the book and a new page begins.
What is in a block?
Each block has two parts:
- A header with information about the block itself: the HashHashA short fingerprint calculated from data, which changes completely if the data is altered by even a single character. of the previous block, a timestamp and a summary of all the transactions in the block. In Bitcoin it also holds a number that miners change over and over until they find a valid solution.
- The transactions themselves, often several thousand per block on the Bitcoin network.
Each block also has a number, its block height, which shows where it sits in the chain. The first block, known as the genesis blockGenesis blockThe first block in a blockchain; Bitcoin's genesis block was created on 3 January 2009 and contains a headline from The Times., is number 0. It was created on 3 January 2009.
How often are new blocks created?
That depends on the network. On Bitcoin, a new block is added roughly every ten minutes on average. Ethereum aims for a new block every 12 seconds.
Whoever creates a block is rewarded for it. In Bitcoin the reward is newly created bitcoin plus the network feesNetwork feeA fee paid to a crypto network, not to a bank or company, for including your transaction in a block. from the transactions in the block. Space in each block is limited, which is why fees rise when many people want their transactions included at the same time.
Everything in Myntkaup Learn is written and regularly reviewed by the Myntkaup editorial team. It is for education and is not investment advice. Editorial policy. Updated 18 October 2026.