Blockchain for Noobs

Blockchain, when explained in very simple words, is storing data in
blocks and making a chain connecting those blocks, forming a
distributed and decentralized system. Here, we list the properties of
blockchain and explain them individually to help you understand
blockchain better.

1. It is a sequence of blocks: These blocks store data or information about transactions of any type and are connected to one another.
2. It is distributed: Instead of one entity or person controlling the entire chain, there are thousands of computers which come up with agreements about which transactions are valid, and every single computer connected to the network has to follow those rules.
3. It is decentralized: There are thousands of machines involved in the system.
4. It is ordered: Every block in the blockchain has a hash, and the hash of the current block depends on the hash of the previous block.
5. It is public: Every machine is connected to one another and every single transaction made is broadcasted to the network. Every transaction is verified using cryptography, and once made, it cannot be modified.
6. It is immutable: Since every block of the chain contains the Hash of the previous one, it is impossible to change any block. If you do so, the entire blockchain becomes unstable, and you have to change the entire chain in order to modify a single block.

How is blockchain secure?

As we already know, every block in a blockchain holds information. In addition to this information, every block also has a unique hash. This hash is derived using cryptography and depends on the hash of the previous block, as well as the information in the current block. Hence, if we want to modify the information in the current block, the hash changes, and we need to modify the entire chain. Hence, it’s not possible to modify any data because of malicious reasons. Since thousands of computers are involved in validating transactions, hacking the network requires you to hack every single computer on the network, which makes it extremely secure.