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RBF replaces an unconfirmed transaction with a higher-fee one spending the same inputs. Since Bitcoin Core 28.0 in October 2024, full RBF is the default, so replacement no longer depends on the sender signalling for it.
Proof of work means only someone who has actually spent computation can add a block. Rewriting history means paying that cost all over again, which is why older transactions become effectively impossible to reverse.
The exact number of global Bitcoin owners is unknown because blockchain records addresses, not people. Triple-A estimated over 560 million global crypto owners (6.8% of world population) as of 2024; Bitcoin-specific estimates vary by hundreds of millions depending on methodology.
On-chain analysis (the "Patoshi Pattern") suggests roughly 1.1 million BTC (about 5% of the supply cap), mined in 2009-2010, remains unspent and is statistically attributed to a single early miner believed to be Satoshi Nakamoto. This is an estimate, not confirmed ownership.
Led by Strategy (formerly MicroStrategy), public companies worldwide are increasingly holding part of their cash reserves in bitcoin. As of July 2026 Strategy is the largest corporate holder at 843,775 BTC, with Twenty One Capital and Metaplanet close behind in the low-40,000s BTC. Holdings don't only grow, though — MARA Holdings sold part of its stack to cut debt. A 2025 accounting-rule change (mark-to-market) and the "mNAV" metric shape these stocks' prices and financing, and corporate treasury strategy operates under very different assumptions than personal investing.
To buy Bitcoin in Japan, use an FSA-registered exchange, complete KYC with a residence or My Number card, deposit yen, and buy from a few hundred yen. Profits are generally taxed as miscellaneous income.
Double-spending is the fraud of spending the same coin twice. Bitcoin prevents this without a central administrator by recording all transactions in chronological order on a single public blockchain, where reversal becomes probabilistically near-impossible as more confirmations accumulate.
The right response to a bitcoin crash is to avoid emotional buying or selling and follow rules set in advance. Historically it has recovered from 75-85% drawdowns from its highs. Avoid panic-selling, over-averaging-down, and adding leverage; use the fear & greed index as a thermometer rather than a signal; and be mindful that taxes on gains realized across a calendar-year boundary generally can't be offset by later losses.
A dusting attack sends tiny amounts of BTC ("dust") widely, then de-anonymizes recipients the moment they spend that dust together with other funds, by linking the addresses together. Dust itself poses no risk of fund loss — the correct response is to leave it untouched and not include it in transactions.
If a pasted destination address changes into a different one, it's usually "clipper" malware silently monitoring the clipboard and swapping in an attacker's address. Defend with full-string verification before sending, using QR codes or a saved address book, small test sends, and a final check on your hardware wallet's own screen.
As of mid-2026, no quantum computer exists that can actually derive a Bitcoin private key. Risk is concentrated in coins whose public keys have already been exposed on-chain (estimated at roughly 20-30% of circulating supply). The developer community is discussing quantum-resistant address proposals (BIP-360/BIP-361), still in draft stage.
A 51% attack rewrites recent blocks with majority hashrate, enabling double-spending and transaction censorship — but it cannot steal other people's coins, forge signatures, or change the 21 million supply cap. It has never succeeded against Bitcoin itself, due to the enormous cost involved.
Whether it's "too late" isn't a question about the price level — it's a question about your risk tolerance and investment horizon. The realistic way to avoid buying the top is to invest only money you can afford to lose, spread across time via dollar-cost averaging, starting small.
The Strategic Bitcoin Reserve was created by a March 2025 executive order (EO 14233) under which the US government holds forfeited BTC instead of selling it. It does not require new taxes or large-scale purchases, and as of July 2026 it is still executive policy rather than law.
下次减半预计在区块1,050,000到达时＝2028年前后，奖励从3.125减半至1.5625 BTC。日期会因出块速度而变动，无法事先确定。价格上涨没有保证。
BTC是以价值存储为目标的PoW型、上限2100万枚的货币；ETH是运行智能合约的PoS型、无上限的基础平台。2022年9月的The Merge使ETH转向PoS。不是孰优孰劣，而是定位不同。
BTC是比特币的货币单位。1 BTC可细分到一亿分之一的「聪」，即使买不起一整枚，也能用几百日元持有。
白皮书是中本聪于2008年10月31日发布的论文《Bitcoin: A Peer-to-Peer Electronic Cash System》。它给出无需中央机构防止双重支付的方法，成为比特币的起点。
硬件钱包把私钥保存在离线专用设备中并在设备内签名、私钥不外泄，因而抗黑客，适合大额、长期持有；比设备本身更重要的是助记词的保全。
多数比特币诈骗都有共同套路：“保证赚钱”加上催促“立刻转账”。了解高收益骗局、冒充、假交易所、假客服、杀猪盘等手法，识别危险信号，并在转账前向当地机构核实。
热钱包常在线、方便但更易被攻击；冷钱包离线、安全但更费事。这是便利与安全的取舍——日常小额放热钱包，长期持有的大部分放冷钱包。
Taproot 是2021年11月14日激活的比特币大型升级（软分叉）。引入 Schnorr 签名后，交易的效率、隐私与智能合约灵活性都得到提升。
比特币发行上限约2100万枚，由代码固定。减半让新币发行逐步减少，最后一枚预计2140年前后；上限达到后矿工以交易手续费为主要收入。
比特币的价值来自稀缺性（2100万枚上限）、抗篡改、转移/保存的便利与社会共识。它没有国家或黄金背书，但本质上法定货币也是如此。
比特币因稀缺性与可转移性被称为“数字黄金”，但缺乏黄金的悠久历史与稳定性，价格波动远大于黄金。二者是性质不同的资产。
比特币转账不可逆：复制并目视核对地址，对新对象或大额先做测试转账。手续费随拥堵（sat/vB）变化，到账通常几十分钟。小额支付可用闪电网络。
中本聪是比特币创始人的化名，真实身份不明，可能是个人也可能是团体。他于2008年发布论文、2009年生成创世区块，约2010年起消失。
闪电网络是比特币的二层支付网络。通过支付通道，小额支付可以近乎即时、手续费极低地完成，适合日常消费，不适合大额或长期保管。
比特币靠三大支柱运作：区块链记录并保护交易、挖矿用工作量证明添加区块并发行新币、减半约束发行节奏，三者共同实现去中心化与可预测的稀缺。
比特币简史：2008年白皮书、2009年创世区块，历经2017年SegWit与Bitcoin Cash分叉、2021年Taproot与萨尔瓦多法定货币、2024年美国现货ETF与第四次减半。
挖矿是矿工用算力通过工作量证明竞争记账权、把交易打包进区块的过程，约10分钟出一块；收入为新发行币加手续费，并使篡改账本成本极高。
比特币安全保管的核心是掌握私钥：小额可用热钱包，长期大额用冷钱包（硬件钱包），并把助记词离线、多处妥善备份，避免依赖交易所托管。
减半是约每21万个区块（约四年）让区块奖励减半的内置规则，2024年4月降至3.125 BTC，下一次预计2028年前后，时点由区块高度决定。
购买比特币六步：在受监管交易所开户、实名认证、入金、买入、安全保管、了解税务。从小额起步并重视自我托管。
比特币是去中心化数字货币，总量上限2100万枚，由区块链和挖矿（工作量证明）保障，新增发行约每四年减半一次。
