A block is a unit of data or digital codes stored on a distributed ledger known as blockchain. These blocks are added to the blockchain in chronological order to create an immutable and permanent chain of data, called a blockchain.Blocks are made up of digital pieces of information, like timestamps, transactions, and transaction records.
Each block contains a unique code known as a hash, which uses cryptography to link it to the preceding block on the blockchain. The hash of a block is also used to differentiate it from other blocks in the chain. The general process of adding blocks to the blockchain is known as mining.
This involves completing complex cryptographic puzzles and confirming transactions that have taken place, in exchange for newly created Bitcoin or other crypto-assets. If a miner successfully completes the cryptographic puzzle, they are rewarded with newly created digital assets and their contribution to the chain is made public for all to see.
Due to the decentralized nature of blockchain technology, blocks are immutable and cannot be changed or reversed without the collaboration of the majority of the nodes comprising the chain. This increases security and allows for trustless peer-to-peer transactions without the need for intermediaries.
Furthermore, since each block is connected to the previous block via a cryptographic hash, it inherently guarantees the integrity of the entire chain—from the first block to the last—making it virtually impossible for malicious actors to modify or delete data.