The simplest way is to describe the Blockchain as follows: A Blockchain is a chain of blocks (so-called Blocks).

Each block contains transaction data, a time code and a reference to the previous block in the chain. By referring to the previous block, anyone in the chain can check whether they own the same Blockchain.

The Bitcoin network is formed by this Blockchain technology. It is a chronological chain of transaction data that cannot be adjusted afterwards. For Bitcoin, every ten minutes all transactions are bundled and put into a block. Such a block is then added to the chain and thus creates a chain of blocking: the Blockchain.

With that, the Blockchain is in fact a kind of database. Thousands of computers around the world keep a copy of the entire Bitcoin transaction history. These computers check whether new transactions are valid. That is also the real power of the (Bitcoin) Blockchain: it is decentralized. It is virtually impossible to shut down the Bitcoin network because you would have to destroy all those copies all over the world at the same time.