🟠 What is a block?
When we talk about crypto we keep throwing around the term “blockchain”, but many people still don’t know what a blockchain is. Even experts in crypto have a hard time explaining it in a way that beginners can understand.
The good news is, you don’t really need to understand in detail what a blockchain is. In a few years it may just be “the internet”. It’s only because it’s new right now, that this term comes up so much.
So the other day a friend of mine asked me “What is a block?” And that’s a really good question! Let me make an attempt to explain:
The blockchain logs transactions. When you send bitcoin from A to B, that is one transaction on the Bitcoin blockchain.
A bunch of those transactions then are bundled up in a block. This block gets attached to the chain of existing blocks. That’s it. A block is batch of transactions that were made on the blockchain. Time stamped and sealed in a way that cannot be reversed.
You can imagine this like a book:
- Each line of text is a transaction
- Each page in the book is a block
- The whole book is the blockchain
The magic about this book is that it has an infinite amount of pages and everyone in the world can access it. Anyone can make transactions at anytime anywhere in the world and they will all have the latest version in the book in real-time.
There are a few nice visualisations that have been made of the bitcoin blockchain. The image above was taken from this website, and here is another fun animated one, where all the transactions are shown as characters hopping on a bus (=block) that leaves every 10 minutes (for Bitcoin, on the right hand side):
There are many different blockchains besides Bitcoin: Ethereum, Doge, Polkadot, Solana, to name a few (and thousands of others..).
Every blockchain has different rules when it comes to block times, block sizes and who gets to issue those blocks. For example, blocks on Bitcoin are produced every 10 minutes on average, and blocks on Polkadot every 6 seconds. If you click on the bus animation above an go to the website, you will also see that the Ethereum buses are leaving much more frequently than the Bitcoin buses on the right.
But this is what they all have in common: a block is a batch of confirmed transactions.
Enjoy your Sunday,
Anja
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