The Block Head and the Block Body of a Blockchain

The two pieces that I mentioned as the block is the block header and the block body. Now, the block body actually contains all the transactions that we're interested in. And really, like the block body could contain any data. And it would still be a blockchain. But the useful way to think of it is transactions into this chain. So for Bitcoin, it would be a normal UTXO type transaction. In Ethereum, it could be anything from deploying a contract to interacting with one or just simple value transfers.