Immutability is defined as the ability of a blockchain ledger to remain unchanged or unaltered.
This extends to the integrity of the data in the blockchain and is overall state.
To better understand this concept, one has to consider the overall structure of a blockchain.
Each block of information, i.e. facts or transaction details, proceed using a hash value.
This hash value consists of an alphanumeric string generated by each block separately.
Each and every block not only contains a hash or digital signature for itself but also for the previous one.
This is important element as it helps ensures that blocks are retroactively coupled together and unrelenting.
In particular, this functionality of blockchain technology also ensures that no entity or individual can infiltrate in the system or alter the data saved to any block.
Is Immutability a Good or Bad Thing?
Blockchains exist as decentralized and distributed in nature. A consensus is made among the various nodes that store the replica of data, better known as a consensus algorithm.
This consensus also posits safeguards the originality of data, which must be maintained at all times.
In this sense, immutability is a definitive feature of blockchain technology and one of its primary tenets.
The concept of immutability also has the ability to redefine the overall data auditing process and makes it more efficient and cost-effective.
However, immutability can be a double-edged sword, facilitating certain types of cyber-attacks or systematic vulnerabilities.
This includes 51% attacks, which occurs when a singular entity or organization is able to take control of the majority of the overall hash rate.
These attacks are particularly problematic as it can potentially cause a network disruption, whereby granting the attacker enough mining power to modify the ordering of transactions.