What is mining?
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A new batch of Bitcoin transactions is generated across the entire network every 10 minutes (for example, A transfers 0.5 Bitcoins to B). These transactions need to be packaged into a "block" and recorded in the blockchain, which is like a large ledger.
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The task of miners is to compete for this right to "package and bookkeep". Whoever successfully packages the transactions and gains recognition from the entire network will receive Bitcoins as a reward from the system (the initial reward was 50 coins, which is halved every 4 years, and now it is about 6.25 coins). This is the source of "mining income".
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Therefore, "mining" essentially involves providing bookkeeping services for the Bitcoin network through computing power competition, while obtaining newly issued Bitcoins. This is also the only way Bitcoin is issued.
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Preventing double-spending: Without a competition mechanism, someone might spend the same amount of Bitcoin repeatedly (for example, A transfers 1 Bitcoin to both B and C at the same time). Through the computing power competition, only blocks recognized by the entire network can be added to the blockchain, ensuring that each transaction is uniquely valid.
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Decentralized consensus: The core of the competition is "Proof of Work (PoW)" — miners need to use their computers to solve a complex mathematical problem (essentially the calculation of random hash values). Whoever solves it first gains the right to bookkeep. There is no shortcut to this problem; it can only be solved by brute-force "trial" with computing power. The higher the computing power, the faster the trial speed, and the greater the probability of winning.
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A rhythm of once every 10 minutes: The Bitcoin system automatically adjusts the difficulty of the mathematical problem to ensure that a new block is generated every 10 minutes on average. If the number of miners increases and computing power rises, the problem becomes more difficult; otherwise, it becomes easier, ensuring a stable bookkeeping rhythm.
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The winning miner broadcasts the new block to all nodes in the entire network.
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Other nodes will check whether the transactions in this block are legitimate (such as whether the transferor has enough Bitcoins, whether there is double-spending, etc.).
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If most nodes recognize it (that is, the verification is passed), this block will be permanently added to the end of the blockchain and become part of the "large ledger".
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Once added, no one can tamper with the content of this block — because the blockchain is a "chain-like" structure, each block contains the hash value of the previous block. Tampering with one block will invalidate the hash values of all subsequent blocks, and to make the entire network recognize such tampering, more than 51% of the computing power needs to be controlled, which is almost impossible due to the extremely high cost.
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Early days: Around 2010, ordinary computers could be used for mining, and some people even mined a large number of Bitcoins with graphics cards.
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Now: Due to the surge in the number of participating miners and computing power, mining has become a professional industry — it requires special ASIC mining machines (with computing power far exceeding that of ordinary computers), and factors such as electricity costs (mining machines consume a huge amount of electricity), venue, and heat dissipation also need to be considered. An ordinary person mining alone may not be able to mine 1 Bitcoin even after several years, so more people choose to join "mining pools" (where multiple people mine together, and rewards are distributed according to the proportion of computing power).
