A distributed ledger is one of the four core technologies of blockchain. If cryptography is the foundation of blockchain, then the distributed ledger is its framework. Simply put, a distributed ledger is a data storage technology—a decentralized, distributed database.

Note that there are two key points to explain here: "decentralization" and "distributed."

First, let’s talk about "distributed." Distributed means storing data in a scattered manner. In the early days, many internet companies would store all our information in a single large database, where data was highly centralized. This is called a centralized database. If such a database encounters problems, severe consequences like system crashes or service unavailability can occur.

Later, these companies realized this approach was too risky. So, they began dispersing data across multiple databases, storing it collectively. Even if one database fails, the others can take over, ensuring the company’s products continue to function normally. This technology of dispersing data storage is what we call a distributed database.

Of course, nowadays, almost all companies use distributed databases.

Blockchain’s distributed ledger is also a type of distributed database. Some might ask: What’s the difference between blockchain’s distributed ledger and the distributed databases used by tech giants?

This brings us to the second point: "decentralization." Blockchain’s distributed ledger is a more specialized form of distributed database. The key difference between it and the distributed databases used by traditional giants is that blockchain is decentralized, while traditional giants operate centralized systems.

For example, imagine a database as a ledger. The centralized databases used by traditional giants are like having multiple copies of this ledger, scattered around to store data collectively. However, no matter how scattered they are, all these ledgers are maintained and managed solely by the giant company itself—no one else has access.

Users who want to check historical data must connect to their central server and send requests. If these centralized giants decide to misuse your data, there’s nothing you can do about it.

In contrast, the decentralized database used by blockchain is formed by connecting individual databases into a large distributed database, where each database has equal permissions to view and store all data.

Compared to centralized databases, blockchain’s distributed ledger disperses the "ledger’s" maintenance power. The ledger is no longer held solely by a giant company but is instead held collectively by everyone. Each person has equal rights, holding a copy of the "ledger." Every transaction is recorded collectively, and periodically, everyone comes together to reconcile the ledger. If anyone tampers with historical records, it can be immediately detected by others.

Moreover, this ledger is completely open to everyone. If you want to participate, you can become a node as long as you gain permission from the blockchain network.
The benefits of distributed ledgers go beyond avoiding single points of failure and reducing the risk of hacker attacks or data loss. They also give blockchain its decentralized nature, preventing data from being concentrated in the hands of centralized giants who might misuse it. This makes "users controlling their own data and deciding its use" a reality.

In summary, the distributed ledger is like the soul of blockchain. In today’s era of big data, cases of centralized giants misusing data are rampant. We hope blockchain can act like a warrior, cutting through thorns and thistles, to put an end to the current chaos of data misuse.