Recap

🤯 Whoa! We’ve covered a lot of new concepts.

Let's summarize what we have learned and go over the key terms. 

Blockchain is designed to enable distributed, decentralized systems to agree on the same version of data. 

The data is entered into blocks and, with new material, blocks are chained together as a blockchain. The data on each block is stamped with a hash algorithm and the blocks are chained together using the hash of the previous block.

This blockchain is shared by different computers, called nodes, but because it is a decentralized system, the computers may start producing conflicting versions of the blockchain.

To prevent this, the system requires every node to mine the block as they are added to the blockchain. A node needs to guess a nonce number for a block that produces a hash number.

Because it is a guessing game, the more nodes that try to guess the same version of the block, the faster they are mined. The system also forces nodes to build on top of the longest chain, which further enforces alignment on the longest chain. As a result, the longest chain becomes the reliable and agreed version of data.

Even though it is possible to hijack the blockchain and inject an alternative version of the data, as the chain gets longer and as more nodes join the network, it becomes increasingly difficult to do so.

This way, a decentralized system can collectively build an agreed-upon version of the data and facilitate relationships or information flows between different players without a centralized authority.