What is Blockchain?

It is a continuous sequential chain of blocks (a linked list) built according to certain rules;
each next block has a hash of the previous block.
This is a global, large-scale distributed registry that works with a million computers and is accessible to everyone. Any values, from money to music, could be stored, moved, exchanged, and managed without powerful intermediaries (such as banks, corporations, up to the state itself). Information is distributed across the global registry. When people can trust each other everywhere and cooperate on equal terms.
And trust is based not on the authority of an organization, but cooperation, cryptography, and smart code