By grouping into blocks every transaction between users within the network. Each block is validated by specialized network nodes, using techniques that depend on the type of blockchain. In the Bitcoin blockchain, the technique used is called “Proof-of-Work” and consists of solving algorithmic problems. Once the block is validated, it is time-stamped and added to the blockchain. The transaction is then visible to the entire network. Theoretically, a block cannot be altered or deleted once it is added to the blockchain. This process guarantees the authenticity and security of the network.