Bitcoin mining explained: what it is and why it is not free money

What miners actually do

Miners gather payments that are waiting to be confirmed and check each one against the network's rules. A payment that breaks a rule is dropped rather than passed on. The valid ones are bundled together into a block, and the block is added to the shared record that every participant can inspect. That record is what people mean when they talk about the blockchain.

The work is bookkeeping with a cost attached, not problem-solving for a customer. No miner is fixing anyone's transaction or answering a request from a user. The block is built, broadcast, and accepted by other nodes only if it follows the same rules everyone else applies. For the wider picture of how the coin itself works, see what Bitcoin is.

Payment comes in two parts. Newly created coins are issued to the miner who adds the block, and the fees attached to the payments inside it go to the same miner. This is the only route by which new bitcoin enters circulation, and the supply is capped at twenty-one million coins.

A single miner cannot rewrite the rules or spend coins that are not theirs. Any block that tries it is rejected by the rest of the network, so the shared record holds only what the majority of participants accept.

Proof of work in plain words

Proof of work is the guessing game that decides who adds the next block. A miner takes the block's data, adds a changing number called a nonce, and runs the whole thing through a hash function. The output looks like random characters, and the miner needs it to fall below a target set by the network.

There is no clever shortcut. The only way to find a nonce that works is to try one after another, so a miner may run through a vast number of attempts before one succeeds. Checking the result is another matter: anyone can run the same hash once and see straight away whether it is valid. That gap is the point — cheap to verify, expensive to produce.

Many machines guess at the same time, and the first to land a valid result wins the right to add the next block and claim its reward. Think of it as a lottery where each ticket is bought with electricity rather than naira: more machines and more power mean more tickets, but a ticket is a chance, not a promise. A small miner can guess for a long stretch and add nothing.

This is also what makes the record hard to rewrite. Changing an old block changes its hash, and every block after it no longer fits. An attacker would have to redo all that guessing faster than the rest of the network does it, while the honest chain keeps growing. The cost of that effort, in power and hardware, is the barrier.

Blocks, rewards and fees

A new block is added to the chain roughly every ten minutes. The network aims for that steady rhythm so that confirmations arrive at a predictable pace, whatever the total guessing power pointed at it. When a miner wins a block, the reward comes in two parts: newly issued coins and the fees attached to the payments included in that block.

The supply of new coins is limited by design. Only twenty-one million bitcoin can ever exist, and the amount issued with each block is scheduled to shrink over time. No committee decides this; the schedule is written into the rules that every node checks. As the issuance steps down, the same cap keeps the total fixed.

Fees therefore carry more weight as time passes. When the new-coin reward is small, the payments miners collect for including transactions make up a larger share of what they earn. A fee is not a fixed charge: it is what a sender chooses to attach, and miners generally favour blocks that pay them more. If you want to understand how those charges work in practice, the guide to bitcoin fees sets out the detail.

Rewards are paid only to the miner whose block is accepted. A miner who guesses without success for hours receives nothing for that effort, which is why the cost of power matters so much.

Difficulty adjusts

The target that a winning hash must fall below is not fixed. The network watches how quickly recent blocks were found and moves that target after a set number of blocks. If blocks are arriving too quickly, the target tightens and guessing becomes harder; if they are slow, it loosens.

This adjustment is what keeps the ten-minute rhythm steady. It does not care who is mining or where they are; it responds only to the pace of blocks actually produced. Every node applies the same rule, so no participant can quietly opt out.

The consequence is easy to miss. Adding machines does not make blocks arrive faster for long, because the network answers by raising the difficulty. What changes instead is the share of the total guessing power each machine holds, and that share shrinks as more miners join.

A miner who doubles their equipment can find the difficulty has risen to match, leaving their odds much as before.

This is why mining drifts toward those with cheap power and efficient rigs. A machine that burns more electricity for the same guesses eats into the reward, and a higher difficulty makes every wasted guess costlier.

Why electricity and special machines are needed

Guessing at hashes is a narrow, repetitive task, and a general-purpose computer is built for many other jobs besides. A laptop or phone can run mining software, but it spends most of its effort on the operating system, the screen and everything else you ask of it. Purpose-built mining machines strip all that away and do little except compute hashes, which is why they squeeze far more guesses from the same electricity.

Those machines draw a lot of power and turn most of it into heat. They are not quiet, either; the cooling fans run continuously and the units are designed to sit in racks rather than on a desk. A phone asked to do the same work overheats, throttles and drains its battery in a short time.

At the scale that matters, mining behaves like an industrial business. Operators negotiate power contracts, arrange cooling, keep spare machines and replace parts when they fail. A miner working from a flat with a domestic supply and an ordinary meter is competing against operations built around those costs.

Unreliable power makes the position harder still. Every outage is time when the machines guess nothing and earn nothing, while the equipment still has to be paid for. Where electricity is expensive or intermittent, the running cost can outstrip what the guesses bring in, which is why so much mining follows cheap and steady power.

Why home and phone mining rarely pays

A single phone or laptop holds a share of the network's total guessing power so small that the odds of it ever finding a block are negligible. You could leave it running for years and still have nothing to show for the electricity. That is not bad luck; it is arithmetic, and it applies to any one small device.

Joining a mining pool changes the shape of the payout rather than the underlying maths. The pool combines everyone's guessing and splits any reward among members in proportion to what each contributed. Your slice is then so thin that, once you subtract the power your device burned, the amount left over can be less than what the electricity cost you.

An app on your phone that claims to be mining deserves suspicion. A phone cannot compete with purpose-built machines, so the app is either doing nothing at all, wearing out your battery with pointless computation, or quietly collecting your personal data. Some combine all three.

Treat mining as what it is: a competitive industrial activity with real running costs, not a savings plan. Money set aside for mining does not grow on a schedule, and a small setup can run at a loss for as long as you keep it switched on. If you cannot state your power cost and your expected share clearly, you do not yet have a case for mining at home.

How free mining sites and apps work as traps

A site that promises free bitcoin for watching a counter climb is selling you a story, not a service. The figure on screen is generated by the page itself; nothing is being mined, because a browser tab cannot compete with purpose-built machines. The counter exists to make the next step feel earned.

Withdrawal is where the trap closes. You are told to deposit a little first, or to upgrade your account, before the balance can be released. Pay, and a new charge appears — a tax, a verification fee, a minimum threshold. Each payment is small enough to seem worth risking against the sum on screen, and that sum is imaginary.

Some cloud mining contracts follow a similar shape. A company sells you a slice of hashing power it claims to run elsewhere, and may pay early buyers from the deposits of later ones. With no machine to inspect, you cannot confirm the power exists.

Some apps ask for access to your wallet, a seed phrase or a signing approval. Treat any such request as a theft attempt. A genuine mining operation needs your electricity and hardware, not your keys.

Fake withdrawal screenshots spread through social media feed the illusion; an image proves nothing. Ask yourself why a real miner, earning from blocks, would need deposits from strangers. The word free is the warning.

Checklist before you trust any mining offer

Use these checks before you send anyone money for a mining offer, and treat a failed check as a reason to walk away.

• Does it ask you to pay before it pays you? A deposit, an upgrade or a release charge is the classic shape of a mining scam.
• Does it promise a daily return? Mining income varies with difficulty and power costs, so a fixed daily figure is a story, not a result.
• Is the company unnamed, or does it hide behind a social media handle? Without a name you can look up, there is nobody to hold to account.
• Can you read the terms in full before paying? Vague or missing terms usually mean the offer is built to be argued about later.
• Does it press you to recruit others? Payment that depends on new joiners is a sign the money comes from people, not machines.
• Can the claim be checked on the public record? Block rewards are visible on the blockchain, so a real operation can point to its own activity.

If you have already paid, stop sending more. Keep screenshots, messages and payment records, tell your bank or mobile banking app about the transfer, and refuse any request for a further payment to release your funds. Read the risk page for how to weigh offers like these.

Buying bitcoin through a regular platform is a different thing from mining, and its steps are set out in the buying guide.