1. What are blocks?

A block comprises a file in which data pertaining to the most recent transactions on the Bitcoin (BTC) network is permanently recorded. Each block can be likened to a page of a ledger, with the blocks “chaining” together to comprise the decentralized ledger that underpins the Bitcoin network.

Those bundled transactions are confirmed by miners before they are added to the Bitcoin blockchain as new blocks. The size of a block creates a limit on the number of transactions that can be verified with each block. As such, larger blocks require greater computation power and will take longer to be mined. Blocks exceeding the limit will be rejected by the network.

During Bitcoin’s infancy, blocks were limited to carry no more than 36 megabytes of transaction data each. However, the block size was reduced to 1 MB on July 14, 2010 in order to counter both the threat of transactional spam clogging up the network and potential distributed denial-of-service (DDoS) attacks.

However, universal consensus regarding an ideal block size was not found, and core developers predicted that the rate of transactions hosted by the network may exceed the available block space in future, arguing in favor of an increase to the 1 MB limit shortly after it was put in place. Since the introduction of the 1 MB block limit, the number of transactions processed per second by the BTC network has largely oscillated between two and seven.

Chart of Bitcoin transactions per second

Source: Blockchain.com

