A blockchain is a distributed, decentralized database that exploits the peer-to-peer technology and that is usable from anyone on the net. In other words, it is a ledger that keeps the history all of the cryptocurrency transactions from its conception. In order for a transaction to happen, the nodes within the 50% + 1 of blockchains must approve the operation. It is an open source system that does not use middlemen like banks to function and to make transactions. Transactions are distributed on nodes that validate them and insert them in the first available block. 

If taken as is, the blockchain can be used in all kinds of technological fields in which there is a relation between individuals. It guarantees trading of shares, titles and goodness of a certain operation, can replace notary deeds, and validate voting systems. This is because each operation is overseen by nodes of the networks that validate or reject the operation and that maintain anonymity.