Block building refers to the process of creating new blocks in a blockchain. Each block contains a list of transactions, a timestamp, and a reference to the previous block, forming a continuous chain. This process is crucial for maintaining the integrity and security of the blockchain.

When a new block is created, it must be verified by network participants. This is usually accomplished through methods like Proof of Work or Proof of Stake. Miners or validators compete to solve complex mathematical puzzles or validate transactions, ensuring that only legitimate transactions are recorded.

Successful block builders are rewarded with transaction fees and, in some systems, new coins. This not only compensates them for their efforts but also incentivizes them to keep the network secure. Through block building, decentralized systems maintain transparency and trust without the need for a central authority.

Each block is immutable and irreversible, making any alterations easily detectable. This trustless system is fundamental to the working of cryptocurrencies and ensures that all participants have a consistent view of the ledger.