Hashes, Blocks, and Blockchains

This is part of a larger article “Explaining How Proof of Stake, Proof of Work, Hashing and Blockchain Work Together.”

Take a look at this video to better explain the fundamental parts of a Blockchain. You can play around with making (conceptual) hashes, blocks, and blockchains here.

• What is a Hash? A hash is the result of a hash function — or a function that simply takes data and converts it to an almost-unique, fixed size 256-bit (32-byte) string of numbers and letters. Here’s an example:

SHA256 + “Hello World” = a591a6d40bf420404a011733cfb7b190d62c65bf0bcda32b57b277d9ad9f146e

Try this here. As you can see, even a small change in the initial data will completely change the hash!

SHA256 + “Hello Worl” = 12fec4c65dd4455c48aff8977a7cd8ccb97539ad4cd7c37f13cf71ba8bee9a98

• What is a Block? A block is a group of transactions in chronological order (or the best chronological order that the miner nodes can agree and organize the transactions in). Every block has, as its data, the hash of the previous block. Each block is made of a Block Header and a “Block Body.”

Here’s a few crucial “Block” facts:

1. The main way of identifying a block in the blockchain is via its block header hash.
2. The block header hash is calculated by running the block header through the SHA256 algorithm twice.
3. A block header hash is not sent through the network but instead is calculated by each node as part of the verification process of each block.

• What is a Blockchain? A chain of Blocks, where each Block references the previous Block’s hash (as seen below)

Let me know if you have any questions!