From a business standpoint, a blockchain can be defined as a platform where peers exchange value / electronic cash without the need for a centrally-trusted arbitrator.
For example, for cash transfers, banks act as a trusted third party. In financial trading, a central clearinghouse serves as an arbitrator between two trading parties.
Disintermediation allows blockchain to be a decentralized consensus mechanism where no single authority is in charge of the database.
Decentralization provides quicker transaction speeds, cost savings, and greater trust.