We specifically study the Genesis block for both the ethereum and bitcoin blockchains.
The Bitcoin Genesis Block: How It All Started
"Every successive block is linked together, hence the term 'blockchain', and according to
AllianceBlock Founder and CTO Matthijs de Vries, this is integral to the security of the blockchain."
"Each block contains information about the transactions in that block and a hash from the previous block it’s linked to.
The next block will contain the hash of all the data from the previous block, and so on: 'the merkle tree,'" Matthijs de Vries told Decrypt. "This ensures that if one transaction gets altered, the whole chain gets corrupted."