Proof of Work To put it simply (and we will explain this here in greater detail) your Proof of Work (POW) is the way the system knows that effort has gone into creating the block. This is how it knows that the lock was not just thrown together and that resources of value had to be expended in terms of time, energy and assets that had to be deployed to do the work that comes up with the solution. The proof of doing the work is contained in the solution to the puzzle. You can guess at it, or you can approach it from a particular direction; you can come at it in any way you want, but the point is that you have to work at it and keep trying until you get it. When you do, and if you are the first one to solve the puzzle, then you get to submit that block as the next in the chain and get your reward for that. The miner first chooses the transaction he wants to place in the block, and then starts to conduct a hashing operation on it. The transaction IDs are placed in a Merkle Root and the rest of the information is added. This, as you saw, includes the time, date, previous block‘s hash and the nonce. This is where the puzzle comes in.