By now, we should know that Blockchain Technology is going to make great impacts in nearly all industries in the future, and for good reasons– financial institutions are finding very clever means to start testing and investing in this technology. Therefore, is it’s importance for us to understand the structure of blockchain and how it works.
The structure of blockchain data is a well-ordered, back-linked list of transaction blocks. The blockchain can be kept in a simple database, or as a flat file. The Bitcoin Core client keeps the blockchain metadata using LevelDB database of Google. Blocks are connected “back”, each referring to the preceding block in the chain. Normally, blockchain is visualized as a vertical stack that has blocks layered on top of each other. The first stack serves as the basis of the stack. The conception of blocks stacked on each other results in the use of the terms such as “tip” or “top” to refer to the most newly added block , and “height” to refer to the distance between the first block and other blocks.
Every block within the blockchain is recognized by a harsh, created with the SHA256 cryptographic hash algorithm on the block header. Every block also references a preceding block, referred to as the parent block. In other words, every block has the hash of its parent in its own header. The series of hashes connecting each block to its parent makes a chain going back to the first block, referred to as the genesis block.
Although a block has one parent, it can momentarily have many children. Each child refers to the same block as its parents and has the same parent harsh. Many children appear when there is a blockchain “fork,” a short-term situation that happens when different blocks are found nearly concurrently by different miners. Ultimately, only s single child block becomes the blockchain part and the “fork” is resolved.
The identity of the child changes if the identity of the parent changes. If the parent block is modified, the parent’s hash changes. Consequently, the parent’s altered hash compels a change in the “preceding block hash” pointer of the child. When the child’s hash changes, this, in turn, necessitates a modification in the pointer of the grandchild, which in turn alters the grandchild, and so on. The cascade effects make sure that once a block has numerous generations, it cannot be tampered with without forcing a recalculation of all successive blocks. Since such recalculation would need enormous computation, the presence of a long chain of blocks ensure that blockchain is immutable, a feature in bitcoin’s security.
To understand the blockchain technology structure, think about layers in a geological formation. With seasons, the surface layer might change. The surface layer can also be blown away before it has time to settle. However, when you go several inches deep, the layers became more and more stable. When you look a hundred feet down, you will see rocks that have remained undisturbed for centuries. In the same way, in blockchain, the recent blocks might be changed easily. But once you go deep into the blockchain, blocks are less and less likely to change. Beyond 100 blocks, there is so much permanency. While the likelihood of any block being changed always exists, the possibility of such an occurrence decreases as time passes until it becomes insignificant.
Well, this may sound too professional to you, but the short and simple fact is that the structure of a blockchain technology makes a block of data extremely difficult to remove or change. When someone wants to change it, the participants in the network, who have copies of the existing blockchain, are able to evaluate and verify the proposed transaction. Hence, enable transparency and accuracy in transactions.