Blockchain is a system of recording information in a decentralised, immutable and transparent way. This means that it is very difficult to change, hack or 'cheat the system' when the share of value, or transactions, are involved.
A blockchain is a digital ledger of transactions that is duplicated and shared across the entire network of systems on the blockchain. This is what makes it secure and immutable.
Many of the top 100 companies by market capitalization use blockchain technology to optimise their processes. These include household names such as Amazon, Samsung and BMW.