8. Other possible blockchains

The general definition of a blockchain could be: a blockchain is a file (a) shared on a peer-to-peer network (i.e., reproduced and stored in each node), (b) secured by strong cryptographic primitives, (c) which evolves only under the control of a community with an interest in its existence, (d) where nothing is deleted, and (e) which increases its content by periodically adding pages linked to one another. Having such a system is a secure way to share information and build trust between distant actors who may not even know each other.

Satoshi Nakamoto invented and cleverly shaped this idea, giving it a specific and open implementation: new players can join at any time, others can leave, everything is public, nothing is encrypted. However, creating decentralized digital currencies is not the only use for this type of peer-to-peer network-based software architecture,...