I just noticed that more and more people are talking about blockchain, but what exactly is blockchain? Why is it so important? What risks does it have? Today, let's take a look.

Simply put, what is blockchain? It is a technology that helps us transmit data securely without the need for intermediaries. That's what blockchain is—its name already suggests it. "Block" (a data segment) linked together in a chain. Each block stores data and is connected with a special code, making it nearly impossible for anyone to modify the data in each block without detection.

How does it work? The interesting point is that blockchain has a very complex protection system, making it almost impossible to secretly alter the data.

Initially, it involves hash codes. Each block has a unique identifier similar to a fingerprint. What blockchain is depends on what data is inside. When data changes, the hash code changes immediately, and that block becomes another block. Moreover, each block also stores the hash of the previous block, linking all blocks together in a way that they cannot be separated.

For example, Block 1 has a hash A24 and contains data transferring 5 bitcoins from Golf to Pu. Block 2 has a hash 12B and contains data transferring 3 bitcoins from Pu to Mali, referencing the hash of Block 1 (A24). Block 3 has a hash 5C3 and contains data transferring 2 bitcoins from Mali to Faa, referencing 12B. If someone tries to modify data in Block 1, its hash will change, which will make Blocks 2 and 3 unverifiable, causing the entire chain to collapse immediately.

The second point is the consensus system. Blockchain isn't stored on a single computer but distributed across many machines simultaneously. When a new block arrives, all machines must verify and agree at the same time. For example, Bitcoin uses a Proof-of-Work system, which takes about 10 minutes to solve the puzzle and create a new block. If someone wants to hack this system, they would need to alter the hashes of all previous blocks before the new block is added, which is very difficult because there are thousands of blocks.

Next, the Peer-to-Peer (P2P) system. Blockchain has no central authority. All users are nodes that store the entire data and verify each other. When a new block is added, all nodes receive it simultaneously, verify its correctness, and store it. To control the system, one would need to control more than 51% of the nodes in a short time, which is practically impossible.

In summary, to tamper with blockchain, you'd need to change the entire chain, reverse the Proof-of-Work process for each block, and control the P2P network—an extremely difficult task.

Currently, blockchain is divided into four types. The first is public blockchain, where anyone can participate, such as Bitcoin, Ethereum, Solana. It is transparent, secure, but slow.

The second is private blockchain, controlled by a single organization. It is fast, secure, but not transparent.

The third is hybrid, combining both types. Some data is open, some is closed.

The fourth is consortium, where multiple organizations jointly control the network.

Regarding strengths, blockchain is a highly secure system. Data is encrypted, unchangeable, and irreversible. It is very transparent because there are no middlemen, reducing costs by avoiding intermediary fees. It allows easy audit trails and saves time.

However, there are weaknesses. The first issue is scalability. It cannot yet handle a large volume of transactions efficiently, though development is ongoing.

Second, theoretically, blockchain can be hacked if someone controls over 51% of the network, but practically, this is nearly impossible.

Third, it consumes a lot of energy because processing and encryption require substantial CPU power.

And finally, there is no clear regulation or oversight, as blockchain was created to change traditional systems like banks and government agencies, which are often reluctant to see it widespread.

In terms of applications, blockchain is a very useful technology. For example, in finance, the Bank of Thailand has the Inthanon project to develop a digital Baht, and JMART has the JFIN project using blockchain for customer data and credit scoring.

In supply chains, IBM created the Food Trust Blockchain, allowing consumers to verify food origins. Other businesses use it to accurately track parcels without the risk of forgery.

In voting systems, blockchain can create tamper-proof voting platforms that are transparent, reduce verification costs, and make changing results very difficult.

Hopefully, now you understand what blockchain is, how it works, its strengths and weaknesses, and its various applications. Welcome to the world of this new technology.