What is blockchain?

a data structure that makes it possible to create a digital ledger of data and share it among a network of independent parties”.

Blockchain For Dummies (Laurance, 2019)

The core concept is that the central database of transactions, the ledger, is managed securely by cryptography and depending on the type of blockchain without the need for a single source of authority.

Typically in a public blockchain such as Etherium this integrity is maintained via a cryptocurrency or transaction fee, rewarded to those who ensure the validity of the networks transactions via Proof of Work, Proof of Stake or Proof of Importance (Danial et al., 2022). In a private blockchain particular users are trusted and given roles that validate the transactions on the ledger instead of using cryptocurrency, such as with an education provider adding degree certificates to a blockchain to prove a learner’s qualifications (Stouffer, 2022).

How does blockchain ensure executed transactions cannot be tampered with?

Once a transaction is added to the ledger it is not easily changed or removed (Cruz, 2022). All activity on a blockchain is transparent to all users, which is validated by advanced encryption and hashing.

What is Blockchain Infographic“, Money.com

Each block in the blockchain is hashed so that the next block can include this hash to confirm its place in the chain. Should someone try to falsify transactions in a block, or add/remove a block from the chain, the hash would not match and reveal the tampering.

This blog post was originally written as part of a project for the BSc (Hons) Cybersecurity with The Open Univeristy by Jonathan Brogan and is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.


Cruz, G.O.R. (2022) What Is Blockchain?Money.com. Available at: https://money.com/what-is-blockchain/ (Accessed: 20 May 2023).

Danial, K. et al. (2022) Cryptocurrency All-In-One For Dummies. John Wiley & Sons. Available at: https://learning-oreilly-com.libezproxy.open.ac.uk/library/view/cryptocurrency-all-in-one-for/9781119855804 (Accessed: 25 May 2023).

Laurence, T. (2019) Blockchain for dummies. Hoboken, Nj: John Wiley & Sons, Inc. Available at: https://learning-oreilly-com.libezproxy.open.ac.uk/library/view/blockchain-for-dummies/9781119555018/ (Accessed: 20 May 2023).

Stouffer, C. (2022) What is blockchain security? An overviewus.norton.com. Available at: https://us.norton.com/blog/privacy/blockchain-security (Accessed: 20 May 2023).

By Jon Brogan

A cybersecurity enthusiast currently pursuing a BSc (Hons) in Cybersecurity with The Open University. With a background in web development and a passion for problem-solving, I'm on a journey to strengthen digital security and share insights along the way.

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