# BLOCKCHAIN IN CRYPTOCURRENCY??? By [Nitin](https://paragraph.com/@nitin-5) · 2023-03-22 --- **What is blockchain?** A blockchain is a collection of records or an electronic database, like a spreadsheet. A blockchain holds larger amounts of information, such as cryptocurrency transaction records, stored in “blocks” or groups, unlike a regular spreadsheet. These blocks are distributed across multiple computers or a “distributed ledger.” Once each block reaches its storage limit, it is “chained” to a block filled previously, and a new block comes into use. Blockchain, sometimes referred to as distributed ledger technology (DLT), makes the history of any digital asset unalterable and transparent through the use of a decentralized network and cryptographic hashing. A simple analogy for how blockchain technology operates can be compared to how a Google Docs document works. When you create a Google Doc and share it with a group of people, the document is simply distributed instead of copied or transferred. This creates a decentralized distribution chain that gives everyone access to the base document at the same time. No one is locked out awaiting changes from another party, while all modifications to the document are being recorded in real-time, making changes completely transparent. A significant gap to note however is that unlike Google Docs, original content and data on the blockchain cannot be modified once written, adding to its level of security. **Why Is Blockchain Important?** Blockchain is an especially promising and revolutionary technology because it helps reduce security risks, stamp out fraud and bring transparency in a scalable way. Popularized by its association with cryptocurrency and NFTs, blockchain technology has since evolved to become a management solution for all types of global industries. Today, you can find blockchain technology providing transparency for the food supply chain, securing healthcare data, innovating gaming and overall changing how we handle data and ownership on a large scale. **How Does Blockchain Work?** For proof-of-work blockchains, this technology consists of three important concepts: blocks, nodes and miners. What Is a Block? Every chain consists of multiple blocks and each block has three basic elements: The data in the block. The nonce — “number used only once.” A nonce in blockchain is a whole number that’s randomly generated when a block is created, which then generates a block header hash. The hash — a hash in blockchain is a number permanently attached to the nonce. For Bitcoin hashes, these values must start with a huge number of zeroes (i.e., be extremely small). When the first block of a chain is created, a nonce generates the cryptographic hash. The data in the block is considered signed and forever tied to the nonce and hash unless it is mined. Is Blockchain Secure? Blockchain technology achieves decentralized security and trust in several ways. To begin with, new blocks are always stored linearly and chronologically. That is, they are always added to the “end” of the blockchain. After a block has been added to the end of the blockchain, it is extremely difficult to go back and alter the contents of the block unless a majority of the network has reached a consensus to do so. That’s because each block contains its own hash, along with the hash of the block before it, as well as the previously mentioned timestamp. Hash codes are created by a mathematical function that turns digital information into a string of numbers and letters. If that information is edited in any way, then the hash code changes as well. Let’s say that a hacker, who also runs a node on a blockchain network, wants to alter a blockchain and steal cryptocurrency from everyone else. If they were to alter their own single copy, it would no longer align with everyone else’s copy. When everyone else cross-references their copies against each other, they would see this one copy stand out, and that hacker’s version of the chain would be cast away as illegitimate. Succeeding with such a hack would require that the hacker simultaneously control and alter 51% or more of the copies of the blockchain so that their new copy becomes the majority copy and, thus, the agreed-upon chain. Such an attack would also require an immense amount of money and resources, as they would need to redo all of the blocks because they would now have different timestamps and hash codes. Due to the size of many cryptocurrency networks and how fast they are growing, the cost to pull off such a feat probably would be insurmountable. This would be not only extremely expensive but also likely fruitless. Doing such a thing would not go unnoticed, as network members would see such drastic alterations to the blockchain. The network members would then hard fork off to a new version of the chain that has not been affected. This would cause the attacked version of the token to plummet in value, making the attack ultimately pointless, as the bad actor has control of a worthless asset. The same would occur if the bad actor were to attack the new fork of Bitcoin. It is built this way so that taking part in the network is far more economically incentivized than attacking it. --- *Originally published on [Nitin](https://paragraph.com/@nitin-5/blockchain-in-cryptocurrency)*