Because there is no central president or central administrative office in a decentralized blockchain, nodes must agree on what transactions are valid via structured protocols.
### Consensus Mechanisms
– **Proof of Work (PoW):** Nodes expend hardware computer energy to solve mathematical riddles, securing ledger stability (e.g., Bitcoin).
– **Proof of Stake (PoS):** Nodes stake native capital tokens to secure the right to validate transactions, maximizing speed and efficiency (e.g., Ethereum).
### The Cryptography Signature Layer
Blockchain utilizes asymmetric public-key cryptography to verify true digital ownership. When you use your private key, you create a digital signature that proves to the network nodes that you are the unique owner of the funds, allowing secure transaction processing.