Blockchain has become a concept that we are starting to hear very often. Sometimes the term “distributed ledger” is used instead of blockchain. Crypto, blockchain, distributed ledger... All these concepts have become widely heard with the entry of Bitcoin into our world, and the idea that these concepts have never existed before and that they are concepts that emerged with the emergence of Bitcoin has taken place in people's minds. The purpose of developing the technologies that are tried to be expressed with these concepts, the reason for the existence of computers that currently mediate the creation and reading of this text (data), and what the engineers trying to develop these devices are trying to solve is the "data problem". These are problems about how to store data and what can be done with this data.
Have you ever noticed a detail like this in workplace scenes in movies from the years when computers first entered our world? There are lots of notebooks, files and papers on the tables where the computers are located; There are many folders on the shelves around these tables. As the ability of computers to store data increased, the writings in those notebooks, folders and papers were somehow transferred to the computer.
In our opinion, we cannot say that among the definitions of what blockchain is in the searches we make on search engines, those that do not mention the concept of data are successful definitions. Blockchain is a special type of distributed ledger that uses cryptographic techniques to record, store, update and verify data by consensus.
Distributed ledger technology was first described in the article "How to timestamps a digital document" published by Stuart Haber and W. Scott Stornetta in 1991. The main problems that gave rise to this technology are;
No transactions can be made without central authorities,
It is not possible to make transactions without intermediaries,
central data is open to manipulation,
It is not possible to make anonymous transactions,
users do not have full control over the data,
As the number of devices participating in the network increases, processing capacities cannot handle this.
DDT is a protocol that allows storing data in multiple interconnected locations. When new data is added to a database, it is updated across all locations. This communication takes place through computer networks. Modification, management, and backup of distributed ledger databases are spread throughout the network. Data is stored in multiple interconnected locations. When an attack occurs, only one of the databases is affected and the rest of the network can continue uninterrupted.
A centralized database is the opposite of distributed ledgers. Data is stored in one place and protected only by authorized parties. Much of the everyday technology we use utilizes centralized databases.
Blockchain is a type of distributed ledger; that is, there are independent computers that save, share and synchronize data between each other. In other words, blockchain stores information by binding it to cryptographic functions. As the name suggests, blockchain stores information in blocks. When this block is full, it is chained to the previous block, creating a chain that timestamps the movement of data and preserves its chronological order. This seems complicated at first glance, but let's discuss what we actually mean.
On the left side there is a visualized shape of interconnected blocks. Each block is actually a custodian of a data packet. To form a complete block, a block must have the cryptographic hash of the previous block (the value resulting from passing the data through the hash function, the block hash), timestamps and data transaction. Since each block contains information about the previous block, these blocks form a chain. To change a data stored in 277314, all subsequent blocks must also be changed.
Satoshi Nakamoto is the anonymous creator of Bitcoin and published the 'Bitcoin whitepaper', which we can call the manifesto of Bitcoin, in October 2008. The main motivation behind Bitcoin was to create "an electronic payment system based on cryptographic proof rather than trust." It used distributed consensus and proof of work using the "one CPU-one vote" idea. Satoshi Nakamoto explains proof of work this way in the 'Bitcoin whitepaper':
“Proof of Work also solves the problem of determining representatives in the majority-based decision-making mechanism. If the principle of one vote per IP address was adopted to form the majority, anyone who could obtain many IP addresses could form the majority on their own. The basis of the Proof of Work mechanism is the principle of one vote per CPU. The longest chain representing the majority decision is also the chain that has provided the most Proof of Work effort. “If the majority of CPU power is controlled by honest nodes, this honest chain will be the fastest growing chain and will surpass its competitors.”
