Changing any information in a block will change its hash sum. To comply with the rules for building a chain, a change in the hash sum must be canceled in the next block, causing a change in your hash sum. In this case, the previous blocks are not affected.
In order to obey the rules for building a chain, a change in the hash sum has to be written off to the next block, causing a change in its own hash sum. In this case, the previous blocks are not affected.
How the system works
In simple words, blockchain is a huge number of tables made in electronic form and combined into a single database. The technology is convenient due to its advantages and ease of operation.
It is difficult to overestimate the potential of blockchain technology, and its main advantage is a well-thought-out structure. The blockchain is based on a table that has hundreds of thousands or even millions of clones in the network. A distributed network is built taking into account the constant updating of information and its protection from outside interference. The information is regularly verified and is under the control of the community. The technology has a number of advantages. The database is not stored on one server, but resides in many places at the same time. This ensures that the records are kept publicly and easily verified by each user.
Reliability and durability
blockchain technologies - resistance to failures. The information stored in a block is the same across the network, so the blockchain cannot be managed by a single authority or have a common point of failure. Since the introduction of the technology in 2008, there have been no significant failures in the system.
Almost all the problems that occur are related to hacking sites or insufficient control of private keys by the user of the cryptonet. In simple words, the causes of problems in the application of the blockchain are human errors. An example to follow is the global Internet network, which has existed for more than 30 years and has shown its effectiveness. Blockchain technology is not inferior to the Internet, and in many aspects is ahead of it. Features of a distributed ledger guarantee maximum accuracy of accounting and user identification. With the help of the blockchain, the legitimacy of transactions is ensured by creating records on millions of PCs.
Source: Bitcoin Fortress