What is the Blockchain?

The technology behind it
This term describes a continuously updated and expandable list of data records. These data sets are called blocks in connection with this technique. These are interconnected using cryptographic methods. With these methods, calculation tasks must be carried out, which can only be solved by frequent testing. This procedure guarantees that sufficient "work" is invested in the encryption procedure. As this approach is very expensive in terms of electricity and materials, attempts at fraud are generally not very worthwhile. In general, each block contains a timestamp, transaction data and a cryptographically secure hash.
Today, the term blockchain generally describes the concept of a decentralized accounting system. This system is characterised by the fact that despite the many participants in "accounting", a consensus can be found on the "correct" state of the bookkeeping. In this accounting system, the content of the accounts is completely irrelevant. The only important thing about the whole system is that the transactions documented in the blockchain always build on each other and confirm the transactions already made as correct. However, they can only do this if they are aware of the transactions already carried out. It is important to know that there are of course several blockchains and not the one.

Further fields of application
Now that we know what the technology is, we can think about the further application of this technology. The application possibilities of this technology are almost unlimited. Probably the best-known field of application are the crypto currencies, as Bitcoin is one. The transactions of the respective crypto currency are stored here using this technology.
Another field of activity would be that of Smart-Contracts. Translated this means as much as "clever contract". This technique is used, for example, to embed credit contracts in a program code. With these contracts, within the block chain, different management or process tasks can then be carried out. The execution of these tasks can be traced in real time by all participants. In addition, this technology is also suitable for very sensitive data, such as health data, land register entries, etc. This data can be viewed by all parties involved at any time and, as mentioned above, the data is managed and controlled in real time. 

History
The term blockchain has been on everyone's lips for several years and is often used as a buzzword on the Internet. However, very few people know exactly what the term means. The history of this technique goes back to the early 90s of the last century. As early as 1991 Stuart Haber and W. Scott Stornetta thought about the cryptographically secured concatenation of blocks. In 2000, a general theory on cryptographically secured concatenations was developed. 
Until 2008, this technology has been quiet for a while. In 2008, Satoshi Nakamoto produced a white paper on Bitcoin. In it he also mentioned a blockchain as a distributed database management system. 
Since then, technology has begun its triumphal procession and is now an integral part of many parts of life. On the contrary, the spread of this technology is spreading and occupying more and more areas.