Blockchain or blockchain is a huge database that contains all transactions that have ever occurred in the past, as well as the data of all wallets that have ever existed. The blockchain consists of interconnected blocks of public data. At the same time, the encryption system mathematically connects all existing blocks with each other, without at all interfering with the reading of information.
Blockchain is also a distributed database. Copies of this record are kept in every bitcoin wallet program with the exception of bitcoin wallets on mobile phones. The level of data protection is unsurpassed and is associated with the specifics of mathematical encryption. The fact is that not a single record in a block can be replaced, since the subsequent mathematical inconsistencies will lead to the need to replace all blocks in the chain.
Thus, each client has his own copy of the blockchain, and at the time of connection with other wallets, this copy is verified. The slightest inconsistency in the copy of the blockchain will result in that block not being able to connect with other blocks and will be rejected.
The blockchain is open to everyone. Anyone can view its contents using parsers or online services. However, to associate any wallet with the identity of its owner is a very difficult task, which only special services are capable of performing, and even then not always.
The blocks that make up the blockchain function as cells for storing transaction data. New blocks for recording new information are created constantly at an average speed of 1 block per 10 minutes. Once a new block is created, it is verified by all other Bitcoin clients and attached to the blockchain. In the future, it will be impossible to change it, and the database will be automatically updated on all nodes (wallets) of the network.
Wallets, which are also clients of the Bitcoin network, perform the functions of network nodes, that is, they synchronize the blockchain itself and transfer new blocks. For the user, the wallet is needed to receive and transmit their transactions and to view the history of their transactions. All wallet data is stored in the wallet.dat file. Losing this file is tantamount to losing all the money in your wallet.
Based on the foregoing, it becomes clear that the blockchain is a decentralized system. In fact, each wallet of each user is its own small independent center, which independently decides on the inclusion of a particular transaction in the list. Therefore, in order to change something in the blockchain, you need to change all the nodes (wallets) in this system. Or at least most of them.
Thus, it is incredibly difficult to cheat the blockchain. From a theoretical point of view, there are ways, but they all require huge investments that will have to be sent at the same time, as well as incredible technical delights, and still all this will be easy to find and easy to solve.
The amount of data in the blockchain is a little more than 100 GB of information. This is exactly how much Internet traffic is needed by the client program to synchronize it.
All users of the bitcoin network can be conditionally divided into 2 groups: ordinary users and miners. Ordinary users make transactions: transfer bitcoins to each other.
Miners form blocks from these records. For each block formed, the system gives the miner a reward in the form of a certain amount of bitcoins. Currently, the amount of this reward is 25 coins.
