What is a blockchain computer?

Visualise three layers, a database layer, a network layer and a state layer.

At the database layer, data is added and once added it cannot be changed. Data is encoded in transactions such and cryptocurrency transfer details or smart contract code. Validators bundle these transaction details into blocks, these validators are the miners.

At the network layer we have numerous nodes and each node holds a copy of the all these blocks. When a node processes a cryptocurrency or smart contract transaction, it broadcasts these details to all other nodes. The miners validate these broadcasted blocks.

Every new block is essentially an update to the state of this computer. Users can interact with the state layer through a user interface on a node. Here a user can conduct a cryptocurrency transaction or create a new smart contract.