RE: BLOCKCHAIN FOR DUMMIES - what would be your explanation? [question from my recent interview]

That's actually an interesting question and I agree with you it's not easy to explain this to a newbie. I would answer the question as follows:

What is a blockchain?

Imagine that you produce some kind of data. Normally you would store this data on your computer or on a database on a server. The problem is that there are safety issues with this. The computer and the server can be compromised and you might loose your data or it might be transformed.

With a blockchain, you send the data to this blockchain in a encrypted form. This data is stored in a kind of block. This block is linked to the previous block and to the next block. So that it becomes impossible to alter the content of the block without having to alter all the blocks before and afterwards. Only you can access this data with a kind of key which you are the only person in the world to own.

The blockchain is maintained by a network of computers that make sure that new blocks are created and verified.

The big advantes of the blockchain

Only you can access and modifiy the data on the blockchain thanks to your personal keys. The blockchain is secured from attacks because it's not possible to alter the content of one block without having to alter all the blocks before and after it. The data is stored on a network and even if a server is down, there will be no chances that the data is lost.

These caracteristiques make a blockchain perfect to store and transfer value, like Bitcoins. A blockchain is also an answer to many different systems were data has to be accessible to many and stored in decentralised secured situation.

Best regards,

achim