What is Blockchain?

Photo by peshkov/iStock / Getty Images

Photo by peshkov/iStock / Getty Images


Blockchain is one of the most talked about technologies of the past decade. Here’s a brief excerpt from a report written by our Fall 2018 Future Innovators of NYC Tech Accelerator students, Applying Blockchain in Business and Society Today:

Blockchain is a decentralized, public ledger technology that records and stores data [2].  It is most commonly used when two or more items, tangible or intangible, are traded. These trades, which are commonly represented in the form of a token for currency, can comprise of nearly anything, from cash for goods to electronic tokens for voting rights. Every time you make a trade, that action is recorded as part of a block with hundreds of other transactions.  From there, that block is assigned a hash, which is then added to the blockchain [3].

            Hashes, which are produced as a result of running data through a hashing algorithm, are central to understanding how blockchain works. For example, if we take the phrase “Hello World” and put it through a hashing algorithm, we will receive an entirely different result from an almost identical phrase like “HELLO WORLD”. Every block in a blockchain has a hash based on the data stored inside it, where any amount of hashed data will produce a hash of the same length. If you were to get the hash for the combined text of all seven Narnia books, you will get a hash of the same length as a simple line of text, “Hey there!”. This means that the size of a block can scale infinitely, though many blockchain networks place limits on their size.

            In addition to each block containing its own hash, they also contain the hash of the block before it, thus the “chain” in blockchain. If you have a blockchain containing two blocks: block A and block B, they will exist in the blockchain in the order A then B. If any data is changed in block A, then the hash of block A will change and will no longer match the hash that block B is expecting. This will invalidate the chain and make it clear that the chain has been tampered with [4].


Written by: CJ Griesmeyer, Jennifer Rhau and Santhoash Subhaschandraboasc 

Additional contributions by: Vicente Gomez

Edited by: Brian Antolin, Program Manager, Linerun


[2] CBInsights, "What is Blockchain Technology," 11 September 2018. [Online]. Available: https://www.cbinsights.com/research/what-is-blockchain-technology/.

[3] M. A. Murray, "A Reuters Visual Guide: Blockchain explained," 15 June 2018. [Online]. Available: http://graphics.reuters.com/TECHNOLOGY-BLOCKCHAIN/010070P11GN/index.html.

[4] CoinTelegraph, "CoinTelegraph," [Online]. Available: https://cointelegraph.com/bitcoin-for-beginners/how-blockchain-technology-works-guide-for-beginners. [Accessed 4 December 2018].


Interested in learning more about blockchain? Complete the form below to get our Accelerator students’ full report on Applying Blockchain in Business and Society Today!

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