This article is a continuation of "What is Blockchain?". I'd highly recommend you to read that first.
The Bridge - No, not the TV show
So our trio, Eki, Dwi and Tri, has figured out a way to secure their chaining blocks using cryptography, but it doesn't end there.
The trio realised early on that it doesn't matter how secure and tamper-proof the protocol is. If this data only has one source of truth, they would be fucked anyway if the computer is lost or hacked.
Hm... What if many computers have identical data? Yes! Peer-to-peer network should do the job!
Peer to peer!
Blockchain is stored in an extensive network of computers called a peer-to-peer network. On this network, we call each computer a node and every node has a copy of the blockchain.
In the case of Eki, Dwi, and Tri, imagine that their chaining blocks of data are not just available on one person's computer but on many more computers.
When a new block of data has to be added to a network, all nodes of this network must check and verify if all data in the block are valid. If all nodes in the network agree that all data are correct, then the new block will be added to every node on that specific Blockchain. The technical term for this is consensus.
There are many different consensus mechanisms used in various types of Blockchains. We're not going to get into details of consensus, but this is how Blockchain demonstrates a secure method of storing data without a centralised party, like banks or corporates.
You got it!
Now you understand how and why Blockchain is a secure data storage method. But you might wonder... How do Eki, Dwi and Tri add a transaction to a Blockchain?
Read next chapter: How do you create a transaction in a Blockchain?