Why is Git not considered a “block chain”?

Question

Git's internal data structure is a tree of data objects, wherein each objects only points to its predecessor. Each data block is hashed. Modifying (bit error or attack) an intermediate block will be noticed when the saved hash und the actual hash deviate.

How is this concept different from block chain?
Git is not listed as an example of block chains, but at least in summaries, both data structure descriptions look alike: data block, single direction reverse linking, hashes, ...).

So where is the difference, that Git isn't called a block chain?

Answer 1

Both Git and Blockchain use Merkle trees as their underlying data structure. Although Git’s internal data structure is a tree of data objects and each data object is hashed and points to its predecessor, Git is not considered as a blockchain because: 

• In terms of implementation, a blockchain is different. Blocks in a blockchain are independently verified several times before getting added to the blockchain. In Git, however, the verification and validation processes for data objects are less sophistication. There are cases where data objects can be committed to the Git repository without prior verification. And if verification is required, only one user can validate changes on a data object. Therefore, the ‘unhackability’ property that blockchain boasts of is not featured in Git. 

• In most cases, the Git repository is not duplicated across servers, meaning that Git is vulnerable to crashes. If a user is working on Git locally and the user’s local disk gets corrupted, the whole Git project including data is lost. Here again, blockchain is different as data is maintained across a plethora of servers. 

• And lastly, it is possible to rewrite or change Git’s history. This is not possible around blockchain. As an immutable ledger, blocks in a blockchain record all transactions that pertain to them in an unchangeable manner. 

Know Blockchain better with Blockchain Training by Intellipaat.