Blockchain: The Key to the World of Cryptocurrencies. A word that sounds like a promise of wealth. But what exactly is Blockchain? Unfortunately, in most books, articles, and discussions, it is either explained in a way that's hard to understand or oversimplified with unnecessary emotional baggage, presented either technically or ideologically. Some see Blockchain as a savior from greedy bankers, while others view it as a tool for building cryptocurrencies that undermine central banks. Which image is closer to reality? The story of Blockchain is not just a tale of mathematical experiments. It's primarily a story of the age-old attempt to record human activities and the value that flows from them. This time, however, the goal is to make it accessible to everyone on equal terms. But will it truly be equal?