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Bitcoin transactions are irreversible, so a mistaken transfer usually can't be recovered. Coins sent to an exchange may be returned if you contact support, but funds sent to a personal wallet or an invalid address are almost always unrecoverable. Prevention is the only real safeguard.
To pay with Bitcoin you simply scan the recipient's QR code or address in your wallet, confirm the amount, and send. Use Lightning for small, instant payments and on-chain for larger transfers; note that spending Bitcoin may count as a taxable disposal.
Hal Finney was a cryptographer who received the first Bitcoin transaction (10 BTC) from Satoshi Nakamoto on January 12, 2009. He developed RPOW in 2004, was known for the "Running bitcoin" tweet, and died of ALS on August 28, 2014.
Bitcoin Cash (BCH) is a cryptocurrency that split from Bitcoin on August 1, 2017. The split was driven by a scaling dispute over the roughly 1MB block size cap, with BCH choosing to enlarge blocks to raise throughput.
You can buy bitcoin for just a few dollars, and it divides down to the satoshi. The goal at first is to get familiar with using it and its price swings; once comfortable, move on to DCA and self-custody.
Fake exchanges and phishing steal login credentials and authentication codes through look-alike domains, counterfeit apps, and fake emails or texts. Always open sites from bookmarks, use two-factor authentication and a hardware wallet, and verify that offshore platforms are properly registered—anyone asking for your seed phrase is a scammer.
Romance scams typically build intimacy on social or dating apps before luring victims into fake "investments" (pig butchering), while tech-support scams use fake virus warnings to get you on the phone and pay via prepaid cards or crypto. Distrust investment pitches from people you've never met and calls prompted by warning screens.
Dollar-cost averaging (DCA) into Bitcoin means buying a fixed amount at regular intervals to average out your purchase price. It curbs buying at a top and reduces emotional decisions, but price-volatility risk remains and gains are not guaranteed.
Celebrity impersonation investment scams start with fake social media ads that misuse the names and photos of famous people or government agencies. Victims are funneled into LINE/Messenger groups where shills and fake trading screens pressure them to send money. The real person is never involved—don't trust the celebrity in the ad, and verify the operator is registered.
The Crypto Fear & Greed Index is a 0–100 market-sentiment gauge from Alternative.me, where 0 is extreme fear and 100 is extreme greed. It's calculated from factors like volatility and volume and is a sentiment reference, not a trading signal.
A bitcoin transaction usually stays unconfirmed because the fee is too low and the mempool is congested. Check the status on mempool.space, then speed it up with RBF (sender) or CPFP (receiver). Avoid double-spending by re-sending.
Historically, lump-sum buying tends to produce higher average returns, but dollar-cost averaging (DCA) reduces buy-the-top regret and psychological strain. The outcome depends on the market, and each approach has weaknesses. Only ever invest money you can afford to lose.
Bitcoin Pizza Day (May 22) commemorates the first real-world Bitcoin payment: in 2010, Laszlo Hanyecz bought two pizzas for 10,000 BTC, worth roughly $41 at the time.
El Salvador became the first country in the world to make Bitcoin legal tender in September 2021, but a 2025 legal amendment tied to an IMF agreement removed the mandatory business acceptance requirement, making it optional. Most countries do not recognize Bitcoin as legal tender.
Without the seed keys, Bitcoin is lost forever when the owner dies. Sound planning combines a backup location, a trusted person, and a will or professional, and balances privacy with security using multisig, passphrases, and timelocks.
Bitcoin address types are identified by the first character: 1 = Legacy (P2PKH), 3 = P2SH, bc1q = native SegWit (bech32/P2WPKH), bc1p = Taproot (bech32m/P2TR). SegWit and later types tend to keep fees lower, and you can send between different types without issue.
Bitcoin transaction fees don't scale with the amount sent — they're set by transaction size (vBytes) × price (sat/vB). You can check current recommended feerates on mempool.space; fees tend to be lower when the network is quiet, but no specific time of day is guaranteed cheaper.
Bitcoin dominance measures BTC's share of the total cryptocurrency market cap. It helps read the market's structure, but rises and falls alone can't determine price direction or trading timing.
Bitcoin's PoW uses electricity as the cost of securing the network through computational competition. Cambridge University's CBECI estimated about 138 TWh per year (roughly 0.5% of global use) in 2025, with one finding that sustainable energy use had risen above 50%. Because assessments vary by calculation method and comparison, it's important to judge by the underlying data and assumptions.
To use Lightning, install a wallet and scan a QR (invoice) to pay, or show your own QR to receive. Wallets are custodial or non-custodial based on who holds the keys; it excels at small, instant payments but each type carries its own risks.
Mt. Gox was the world's largest Bitcoin exchange of its time until it lost roughly 850,000 BTC and collapsed in 2014. It showed the world the risk of leaving coins on an exchange and helped launch Japan's crypto regulation; creditor repayments began in July 2024.
If you lose your private key (seed phrase), your Bitcoin is generally unrecoverable and there's no rescue desk. Coins held on an exchange may be restored via support. The one safeguard is a secure seed phrase backup.
A Bitcoin node is a computer that stores the blockchain and verifies that transactions don't break the rules. Unlike mining, it earns no reward — it's the network's rule-enforcing guardian. Running your own full node lets you verify for yourself instead of trusting others, and improves your privacy.
Market cap is a metric of a crypto asset's size, calculated as "price × circulating supply." It's useful for comparing relative scale, but note that it is not the same as liquidity — you can't necessarily cash out at that figure.
A passphrase is an optional BIP39 string (the 25th word) that, added to your seed, generates a separate hidden wallet. It keeps funds safe even if the seed is stolen, but if you forget or mistype it, recovery is impossible—so store it reliably and separately from your seed.
Multisig is an m-of-n scheme in which m signatures out of n keys are required to spend bitcoin. Because one stolen key can't move funds and one lost key can still be recovered, it is stronger than single-sig against both theft and loss.
SegWit (Segregated Witness) was an upgrade added to Bitcoin in August 2017. It separated signature data to effectively boost capacity and fixed transaction-ID malleability. Implemented as BIP141, it became the foundation for the Lightning Network.
Bitcoin's difficulty adjustment happens every 2,016 blocks (about two weeks) and automatically keeps blocks roughly 10 minutes apart even as miners join or leave, supporting network stability and a predictable supply.
A Bitcoin confirmation is the number of blocks stacked on top of the block containing your transaction. Blocks arrive on average about every 10 minutes, rollbacks get harder as confirmations grow, exchanges typically require 1 to 6, and 0 confirmations still carry double-spend risk.
The mempool (memory pool) is the waiting room where unconfirmed transactions wait, held in memory by each node. When transactions outpace block production, it congests and the per-unit fee (sat/vB) rises in the fee market. You can check congestion and feerates on mempool.space.
A UTXO (Unspent Transaction Output) is a "chunk of unspent money" on Bitcoin. Your balance is the sum of your UTXOs, not an account figure; sending spends UTXOs in full and creates change, and the number of UTXOs used affects the fee.
For individuals, home Bitcoin mining is very unfavorable today. Profitability hinges on four factors — electricity, hashrate, difficulty, and rewards — while the field is dominated by large operators running SHA-256 ASICs. Difficulty keeps rising and rewards halve at each halving, so no profit is ever guaranteed.
Your seed phrase (12–24 words) is the lifeline for restoring your wallet. Record it offline on paper, split it across multiple secure locations, and never screenshot, cloud-save, or share it — anyone who asks for your phrase is a scammer.
Ordinals are an inscription system that writes data onto individual satoshis (2023); Runes, released at the 2024 halving (block 840,000), issue fungible tokens. Both are debated new uses that can raise fees.
