Parent blocks are the first blocks in a blockchain. A parent block is the origin of a blockchain, meaning it is the starting point for its chain of blocks. Blocks are chained in such a way that each subsequent block references the parent block of the previous block in the chain. The parent block is a special type of block in a blockchain which is often referred to as the “genesis block”.

A parent block is the only block that does not contain a reference to the previous block. It does however contain an output, a transaction list, a timestamp and a difficulty value. It is the first block in the blockchain and all later blocks reference it.

The first parent block is typically hard-coded into the blockchain software and is determined by the consensus protocols of the network. It contains the relevant parameters that define what the blockchain is and the rules that will govern it. This includes the rules which govern mining difficulty, block reward and transaction fee structures.

Once a parent block is successfully accepted into the blockchain, new blocks can be mined and added to the chain. Each time a new block is mined, it is connected to the previous block in the chain (the parent block) via a cryptographic link. This link allows each new block to be identified and verified by participants in the blockchain network.

By referencing the parent block, the blockchain can ensure the order in which the blocks are added, meaning that the entire blockchain can be kept up-to-date with real-time updates. This is a critical aspect of the blockchain technology, as it allows for rapid and efficient verification of transactions on the network.

The parent block in a blockchain is the basis of secure and immutable records. Because the parent block is the source of the chain, all subsequent blocks must be linked to it and any change to the parent block would also change all other blocks. Thus, it stands to reason that if the parent block is secure, so are all of the subsequent blocks in the chain. This security gives users confidence in the data stored on the blockchain, allowing them to transact without fear of being hacked or having their data stolen.

In summary, a parent block is the first block in a blockchain and typically carries the majority of the parameters that will define the blockchain. All subsequent blocks are linked to the parent block via a cryptographic link, making it an important part of the overall blockchain structure. As all blocks are linked to the parent block, it becomes a secure foundation for transactions on the network, giving users confidence in the transactions they make.