You use a blockchain when you want one common ledger across multiple companies, and you don't want to pay/trust a single company to manage it. Not really, you

You use a blockchain when you want one common ledger across multiple companies, and you don't want to pay/trust a single company to manage it. Not really, you can have a blockchain managed by a single company. In the most basic definition, a blockchain is simple an authenticated linked sequence of records. It can be public or not, it can be processed centrally, distributed across a single organization, or distributed in a peer-to-peer fashion.