The blockchain is an innovative technology based on a distributed ledger shared between all nodes involved in the network. The nodes communicate with each other and manage data, which are transactions, according to a specific communication protocol. The blockchain allows transactions to be validated and stored in the distributed database shared across all the decentralized nodes. The transactions are public so that anyone can retrieve and verify them. Additionally, the transactions recorded in the distributed ledger are stored permanently and become immutable. The recent distributed ledger technology enables the deployment of smart contract onto the network nodes. Smart contracts are distributed apps (dApp) executed from all the nodes of the peer-to-peer network, that compute and agree on the results validating them.