Each block points back to the previous block, which creates the blockchain.
Proof-of-work from zero
What is Bitcoin mining?
Bitcoin mining is the race to find a valid proof-of-work for the next block. Miners are not solving a puzzle with cleverness. They are trying huge numbers of guesses until one hash is low enough.
Core ideaGuess hashes
Winning hashBelow target
Average block10 minutes
Mining in plain English
Bitcoin is a public record of transactions. To add a new page to that record, miners collect transactions into a block and then search for a special hash. The hash has to be below a target set by the Bitcoin network. A lower target means fewer hashes qualify, so mining becomes harder.
The work is expensive to repeat, but easy for everyone else to check. That is the security idea: rewriting old blocks would require redoing the proof-of-work and catching up with the rest of the network.
The five words beginners need
The same data always makes the same hash, but tiny changes create completely different results.
Miners change the nonce so they can keep trying new hashes for the same candidate block.
If the hash is lower than the target, the block is valid. If it is higher, the miner tries again.
Difficulty adjusts so blocks keep arriving roughly every ten minutes even as global hashrate changes.
A pool coordinates miners. A solo pool gives real work but pays only if your worker finds the block.
Why mining uses energy
The energy use is not a bug in proof-of-work; it is the cost that makes the ledger hard to rewrite. Miners prove they spent real-world resources searching for a valid block. Nodes can then verify the proof very quickly, without trusting the miner.
This does not mean every mining setup is sensible. A CPU lottery miner is a learning experience. Industrial Bitcoin mining is a separate business with specialized hardware, electricity costs, heat, noise, and risk.