Blockchain is a general purpose technology to exchange informations and\or values between people, without a central server who give it thrust. Out of cryptovalues world it has a lot of applications, like in the medical field: some experimental sanitary system adopt it to keep up-to-date and online medical files of patients or the business plan of the structure, with a very high level of thrustness. Without blockchain everyone in hospital can access a pc and change health informations about patients. With blockchain, to do a change like this, you need your private key as digital sign.