Blockchain — A Short and Simple Explanation in Pictures

A Blockchain is a method of storing data. Data is stored in blocks which are linked to the previous block.

But what does a “Block” look like?

Each “block” contains

1. Data of transactions
2. A unique fingerprint for all the data in the block called a hash
3. A hash of the previous block’s data

What does each of these items mean?

Data in the block usually consists of transactions. A block can contain hundreds of transactions. Alice sending Bob $100 is an example of a transaction in a block

A hash is a unique combination of letters and numbers. It is like a fingerprint for the data in a block and it is always unique to every block in the Blockchain. When the data in a block changes, the hash will also change.

Hence in a transaction, if the amount being sent Alice to Bob changes from $50 to $100, the hash of the block will completely change.

A block also contains the hash of the previous block. Hence forming a chain structure. Combining the above three together, this is what a Blockchain will look like

Now if a transaction in any block changes, the hash of the block will change. When the hash of the block changes, the next block will show a mismatch with the previous hash that was recorded by it.

This gives Blockchain the property of being tamper-resistance as it becomes very easy to identify when data in a Block has changed.