A block in Bitcoin is a structure that stores confirmed transactions. Each block contains transaction data, a hash of the previous block, and other technical parameters, forming a continuous chain – a blockchain.
A new block is created by miners who collect unconfirmed transactions, form a block from them, and solve a complex mathematical problem (proof-of-work). Once the problem is solved, the block is added to the blockchain and becomes part of the network.
The maximum block size in Bitcoin is about 1 megabyte (MB). With the introduction of SegWit (separated certificates), an effective size of up to 4 megabytes is possible, but the base limit remains 1 MB.
A block contains: a list of transactions, a hash of the previous block, a timestamp, a nonce (a number found by the miner), the network difficulty, and a Merkle hash that combines all transactions into one structure.
Blocks are the basis for storing and confirming all transactions in the network. They form a blockchain - a distributed database that ensures the security and transparency of the entire system.
A block hash is a unique cryptographic 'fingerprint' created by the SHA-256 algorithm. It identifies a block and links it to the previous one (via the hash of the parent block).
The block header is the part of the block that contains key information: the hash of the previous block, the Merkle hash, the timestamp, the difficulty, the nonce, and the version. It is the header that is involved in the mining process.
On average, a new block appears every 10 minutes. This time is adjusted automatically: if miners find blocks too quickly, the network increases the difficulty; if slowly, it decreases it.
Block time is the period between the creation of two consecutive blocks. In the Bitcoin network, it is on average 10 minutes, but can vary due to the probabilistic nature of mining.
The block size determines how many transactions can be included in one block. The size limit affects network throughput and fees: when there is congestion, users are forced to pay more to have their transactions processed faster.
