a definition of blockchain -- 1/02/19
Today's selection -- from The Story of Blockchain by Omid Malekan. A definition of blockchain:
"The simplest definition of a blockchain is a technology that allows for something digital to exist in only one place. Imagine if you could download a music file and enjoy it with all of the conveniences of digital technology, but with one difference: The moment you sent it to your friend to listen to, you yourself no longer could.
"The blockchain achieves this feat by combining multiple technologies, from cryptography to peer-to-peer networks (the same ones, ironically, that powered Napster), to form a decentralized and distributed public ledger of who owns, or has access to, something, at any given moment in time.
"Let's say that you were the first person ever to purchase a digital music file from a record label via a blockchain. As soon as the transaction happened, a network of independent computers around the world would communicate with each other and write into the ledger that ownership of a file has been transferred from a record company to you. Let's also say that after you finished listening to the song, you decided to send it to a friend. After first confirming that you in fact own the file by checking the existing entries in the ledger, all of those computers would then agree on the transfer to your friend, and enter that exchange into the ledger as well.
"Follow this process across thousands or even millions of transactions, and you can see how the blockchain preserves the integrity of ownership. Everyone knows who owns what, because everyone can follow the existing ledger back to the beginning of time. There is no room for dispute. Whenever you receive something, the community has already made sure that the sender actually owns it, by looking at the path of how they acquired it.
|Blockchain formation. The main chain (black) consists of the longest series of blocks from the genesis block (green) to the current block. Orphan blocks (purple) exist outside of the main chain.|
"In some ways, this process is similar to how your local municipality tracks the ownership of property, and has done so for centuries. By going to the local clerk's office, you can look up who owns a house you might be interested in buying. By looking at the chain of previous owners, you can make sure the current seller is the rightful titleholder. The blockchain digitizes this process while also improving it.
"The clerk's office is a centralized store of information, and history has proven time and again that such places are fragile. If the office doesn't keep proper backups, vital information might be lost. If an employee makes a mistake in entering a transaction, it might go unnoticed. Worse yet, a malicious actor could bribe the office to change a record after the fact, or even submit forgeries to wrongly transfer a property to their name. The blockchain does away with these vulnerabilities.
"Because the system is distributed, copies of the same chain are kept at thousands of independent locations around the world by different participants. Because it is decentralized, it cannot easily be penetrated or changed by any one bad actor. Since nobody owns the blockchain, it is almost impossible to corrupt it in its entirety. This integrity is accomplished by the consensus mechanism, the process by which independent volunteers continuously come to agree on who owns something today and who should rightfully own it tomorrow."