Learn crypto
97 guides, each starting with a short answer you can read in 20 seconds, then going as deep as you like.
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Crypto basics
What is cryptocurrency?Cryptocurrency (also written crypto currency, or just crypto) is digital money that isn't issued by a bank or government.Cryptocurrency, beyond the hypeCryptocurrency is a shared record of who owns what, kept by thousands of computers that follow the same rules instead of one bank.List of cryptocurrenciesThe best-known cryptocurrencies include Bitcoin (2009), Litecoin (2011), XRP (2012), Dogecoin (2013), Ethereum (2015), the stablecoins Tether (USDT) and USD Coin (USDC), and newer networks such as Cardano, Solana, Avalanche and Polkadot.How does cryptocurrency work?You sign a transaction with your private key.What is a blockchain?A blockchain is a record of transactions grouped into blocks, where each block contains a fingerprint (a hash) of the one before it.Coin vs. tokenA coin is the native currency of its own blockchain, like BTC on Bitcoin or ETH on Ethereum.What is an altcoin?An altcoin is any cryptocurrency other than Bitcoin; the name is short for "alternative coin." Ethereum, XRP, Solana, stablecoins and memecoins are all altcoins.What is Web3?Web3 is the idea of a next version of the internet built on blockchains, where users hold their own money, identity and digital items in a wallet instead of keeping them in accounts run by big companies.What is a satoshi?A satoshi, or "sat," is the smallest unit of bitcoin: one hundred-millionth of a BTC (0.00000001 BTC).What does HODL mean?HODL is crypto slang for holding a coin long term instead of selling when the price drops.How many cryptocurrencies are there?It depends what you count.Digital, virtual and crypto currency: what's the difference?Digital currency is any money that exists in electronic form, including your bank balance, payment-app balances, central bank digital currencies and crypto.Is crypto dead?No.The history of cryptocurrencyCryptocurrency grew out of decades of work on digital cash.
Bitcoin
What is Bitcoin?Bitcoin is the first cryptocurrency: digital money with no company or government in charge, launched in 2009.Who created Bitcoin? The Satoshi Nakamoto storyBitcoin was created by Satoshi Nakamoto, a pseudonym for a person or group whose real identity is unknown.What is crypto mining?Crypto mining is the process of using computers to add new blocks of transactions to a proof-of-work blockchain like Bitcoin.Can you buy part of a bitcoin?Yes.Can you still mine Bitcoin at home?Yes, anyone can still run Bitcoin mining software, but with the whole network at roughly 969 EH/s (October 2026), a home computer will essentially never find a block.What does a bitcoin look like?Bitcoin doesn't look like anything physical: it's digital, and there is no official coin or note.Bitcoin Pizza Day: the 10,000 bitcoin pizzasOn May 22, 2010, Florida programmer Laszlo Hanyecz paid 10,000 bitcoins to have two Papa John's pizzas delivered, one of the first known purchases of real goods with bitcoin.What is the Bitcoin Lightning Network?The Lightning Network is a second layer on top of Bitcoin for fast, cheap payments.ASIC vs. GPU mining, and how mining pools payBitcoin is mined almost entirely with ASICs: machines built to do one hash function (SHA-256) far faster and more efficiently than any graphics card (GPU) or computer chip.
Ethereum and other networks
What is Ethereum?Ethereum is a blockchain that can run programs called smart contracts, which power tokens, stablecoins, trading apps and more.Who created Ethereum? Vitalik ButerinEthereum was proposed by Vitalik Buterin, a Russian-Canadian programmer, in a white paper in late 2013, when he was 19.What is Ethereum Classic?Ethereum Classic (ETC) is the original Ethereum blockchain that continued after the 2016 "DAO" hack, when most of the community chose to rewrite history to return stolen funds.What is ENS (.eth names)?ENS, the Ethereum Name Service, lets you register a readable name such as alice.eth and point it at your wallet address, like a domain name for crypto.What is Litecoin?Litecoin (LTC) is a cryptocurrency launched in October 2011 by former Google engineer Charlie Lee, based on Bitcoin's code.XRP vs. Ripple vs. the XRP LedgerRipple is a private US company that builds payment software.How to buy Ripple (XRP) safely, and where to buy itTo "buy Ripple", you buy XRP: the coin of the XRP Ledger.What is a stablecoin?A stablecoin is a cryptocurrency designed to keep a steady value, usually exactly $1.USDT vs. USDC vs. DAI: how the big stablecoins differUSDT (Tether) and USDC (Circle) are issued by companies that hold reserves and redeem coins for dollars; DAI is created by the Sky (formerly Maker) protocol against collateral that users lock in smart contracts.How to stake Ethereum (ETH): the four ways and their risksYou can stake ETH four ways: run your own validator with 32 ETH (solo staking), join a staking pool with less, buy a liquid staking token that represents staked ETH, or let an exchange stake for you.NFT meaning: what is an NFT?NFT meaning: an NFT (non-fungible token) is a unique token on a blockchain that records who owns a specific item, usually a digital image, collectible, ticket or membership.NFT marketplaces and creator royalties, explainedAn NFT marketplace is a website and set of smart contracts where people list and buy NFTs; the NFT itself lives on the blockchain, not on the marketplace.NFT gaming and play-to-earn: how it works and what went wrongNFT games, also called blockchain or web3 games, make in-game items, characters or land into NFTs that players own in their wallets and can sell, and some pay rewards in tokens.What is a smart contract?A smart contract is a program stored on a blockchain that runs automatically when its conditions are met, for example swapping one token for another or releasing a loan.What is DeFi (decentralized finance)?DeFi, short for decentralized finance, is financial services such as trading, lending and borrowing run by smart contracts on a blockchain instead of by banks or brokers.What is yield farming?Yield farming means putting crypto to work in DeFi apps, usually by lending it or adding it to a trading pool, to earn fees, interest and bonus reward tokens, and often moving it around to chase the highest rate.What is a DAO?A DAO, or decentralized autonomous organization, is a group that makes decisions by votes recorded on a blockchain, usually one vote per token held, and keeps its money in a smart contract that only moves when a vote passes.What is a memecoin?A memecoin is a cryptocurrency inspired by an internet joke, meme, celebrity or trend, with little or no use beyond being bought and traded.What are layer 2 networks?A layer 2 is a separate network that processes transactions cheaply and quickly, then posts a summary back to a main blockchain (layer 1) such as Ethereum, borrowing its security.What is proof of work?Proof of work is how Bitcoin decides who adds the next block.What is proof of stake?In proof of stake, validators lock up (stake) the network's coin as a deposit.
Blockchain technology, in depth
Blockchain technology libraryA guided path from hashes and signatures to rollups, bridges and zero-knowledge proofs.What is a hash? SHA-256 and Keccak-256With a live demo: change one letter and watch the fingerprint change.Consensus mechanisms and finalityHow thousands of computers agree on one history.Rollups, data availability and blobsThe technology behind cheap Ethereum transactions.Bridges and why they get hackedRonin, Wormhole and Nomad, and how to judge a bridge.
Wallets and sending
What is a crypto wallet?A crypto wallet, also called a blockchain wallet, is an app or device that stores the private keys controlling your crypto.Hot vs. cold wallets, and what cold storage meansA hot wallet keeps its keys on a device connected to the internet, like a phone app, browser extension or exchange account.Custodial vs. non-custodial walletsWith a custodial wallet, a company such as an exchange holds the keys to your crypto and you log in with a password.What is MetaMask?MetaMask is a free self-custody crypto wallet, available as a browser extension and a phone app, mainly for Ethereum and compatible networks, plus Solana and Bitcoin.What is a hardware wallet?A hardware wallet is a small device, often like a USB stick, that stores your private keys offline and signs transactions inside the device.Public key vs. private keyYour private key is a secret number that lets you spend your crypto; never share it.What is a seed phrase?A seed phrase (also called a recovery phrase or secret recovery phrase) is a list of 12 or 24 ordinary words that a self-custody wallet creates.What happens when you send crypto?When you press send, your wallet signs the transaction and broadcasts it.How to look up a crypto transactionA block explorer is a free website that shows everything on a blockchain.Crypto transaction fees and Ethereum gas fees explainedWhen you buy or send crypto you may pay several fees: a network fee to the miners or validators who process the transaction, a trading fee to the exchange, a spread (the gap between buy and sell prices), and sometimes a withdrawal fee.
Buying and money
What is a crypto exchange?A crypto exchange (cryptocurrency exchange, sometimes written "cryptoexchange") is a platform where you buy, sell and swap cryptocurrency.Centralized vs. decentralized exchanges (CEX vs. DEX), and brokersA centralized exchange (CEX) is a company that holds your money and crypto and matches your orders on its own books.How to buy Bitcoin safelyThe safest way for most beginners is to buy a small amount through a well-known, regulated exchange or brokerage you reach by typing its address yourself, secure the account with app-based two-factor authentication, and move larger long-term holdings to a wallet you control.How to buy EthereumBuy ETH through a reputable, regulated exchange or app you reach directly, secure your account with app-based two-factor authentication, and if you move it to your own wallet, choose the network carefully: ETH on Ethereum and ETH on a layer 2 like Base or Arbitrum are on different networks.How to calculate crypto profitProfit = what you received when you sold (after the sale fee) − what you paid in total (including the purchase fee).How to find your crypto break-even priceYour break-even price is the selling price at which you'd get back exactly what you spent.Crypto vs. stocks and ETFsA stock is a legal share of a company, with a claim on its profits and rights as an owner.What is staking in crypto?Staking means locking up coins to help run a proof-of-stake network in return for rewards.Crypto taxes: the basics (US)In the US, the IRS treats crypto as property.Accepting crypto payments as a businessMost businesses that accept crypto use a payment processor (gateway): it shows the customer a price locked in dollars for a few minutes, receives the crypto, and settles to you in dollars or a stablecoin, so you never hold a volatile coin unless you choose to.Sending money abroad with crypto: does it really cost less?Sending a stablecoin like USDC across a low-fee blockchain can cost cents and arrive in minutes, while traditional remittances averaged 6.36% of the amount sent in the World Bank's latest global figures (2025).
Investing, retirement and inheritance
How to invest in crypto: a careful beginner's planDecide how much you could lose without it hurting your life, buy through a regulated platform or a spot ETF, start with well-established coins, consider buying small amounts on a schedule rather than trying to time the market, store long-term holdings safely, and keep records for taxes.How crypto portfolios are built: diversification and risk sizingBuilding a crypto portfolio is mostly about sizing, not picking: deciding what share of your total savings could fall 70–80% without hurting your life, then spreading that amount thoughtfully.How do people value crypto assets?There is no accepted way to calculate what a cryptocurrency is "worth".What is a Bitcoin ETF?A Bitcoin ETF is a fund that trades on the stock market and tracks the price of bitcoin.XRP ETFs explainedSpot XRP ETFs are funds listed on US stock exchanges that hold XRP and track its price.Crypto IRA explainedA crypto IRA is an individual retirement account that holds cryptocurrency or crypto funds.How to put crypto in a trust and pass it onYou can hold crypto in a living trust by putting exchange accounts in the trust's name, or by moving coins to a wallet the trust owns.
Markets and trading
Crypto market cap explainedMarket cap is a coin's price multiplied by the number of coins in circulation.How to read a crypto chartA crypto chart shows past prices over time.How to research a cryptocurrencyInstead of asking whether a coin's price will go up, ask what it does, who controls it, how many coins exist and who holds them, whether people actually use it, whether it's been hacked, and whether you could sell it.Why is crypto going down, and will it go back up?Crypto usually falls when investors turn cautious: rising interest rates, bad news, big holders selling, or traders who borrowed money being forced to sell.Will Bitcoin hit $1 million?Nobody knows.Can you day trade crypto?Yes.Crypto futures explainedA crypto futures contract is an agreement to buy or sell a cryptocurrency's value at a set price on a future date.Paying for crypto: card, Apple Pay or bank transfer?A bank transfer is usually the cheapest way to buy crypto.
Going deeper
Is crypto anonymous?No.What is a CBDC? Central bank digital currency explainedA CBDC (central bank digital currency) is a digital form of a country's own money, issued directly by its central bank, such as China's e-CNY or the proposed digital euro.Types of bitcoin: BTC and the look-alikesThere's one original Bitcoin, ticker BTC, on the Bitcoin network.How to create a cryptocurrencyThere are two ways: build a whole new blockchain with its own coin (a huge software and security project), or create a token on an existing blockchain like Ethereum or Solana, which can take minutes and a small network fee.Blockchain analytics: how on-chain analysis traces cryptoBlockchain analytics is the practice of studying public blockchain data to group addresses that likely belong to the same owner, label them (an exchange, a scammer, a ransomware group), and follow money between them.Real-world blockchain use cases: what worked and what didn'tBlockchains have proved most useful where several parties who don't fully trust each other need a shared record that no single one controls, and where money or tokens move on it, which is why payments, stablecoins and tokenized assets are the clearest successes.Crypto and blockchain careers: roles, skills and a learning pathCrypto careers span smart-contract and protocol engineering, security auditing, data analysis, compliance and investigations, product, design, writing and community work.What is an ICO (initial coin offering)?An ICO (initial coin offering) is when a crypto project sells newly created tokens directly to the public to raise money, usually in exchange for ether or bitcoin.Crypto's environmental impact and energy useBitcoin's mining uses a lot of electricity: Cambridge University estimated about 138 terawatt-hours a year in its April 2025 report (based on mid-2024 data), roughly half a percent of global electricity, with a preliminary figure near 190 TWh for December 2025.Crypto crime and money launderingCrypto is used for crime, but it's a small share of all activity.
Safety
Before you send crypto: the safety checklistBefore you send crypto or approve anything in your wallet, stop and check: is anyone rushing you, did you reach the site yourself, are the coin, network, address and amount right, what permission are you granting, and is anyone asking for your seed phrase? If anything feels unclear, don't approve it yet.Fake crypto trading sites: how to check oneNo one keeps a complete list of fake crypto trading sites, because scammers launch new ones every day.Crypto scams: how to spot themCrypto scams usually rely on persuasion rather than hacking: someone builds trust or creates panic, then gets you to send crypto, buy it at an ATM, or reveal your seed phrase.What is a rug pull?A rug pull is a crypto scam where the people behind a token or project attract buyers' money and then suddenly take it, by selling all their tokens, removing the funds from the trading pool or using hidden code, leaving buyers with tokens that are worth almost nothing.What is a crypto airdrop?A crypto airdrop is when a project gives away free tokens to many wallets, usually to reward early users or spread ownership of a new token.Sent crypto to the wrong network?If you sent crypto on the wrong network but to an address you or an exchange control, it can often be recovered, sometimes by contacting the exchange.Bitcoin ATMs: how they work, fees and scamsA Bitcoin ATM (or crypto kiosk) is a machine that lets you buy bitcoin with cash and send it to a wallet address you scan.
Laws and regulation
Crypto regulation by countryWhere crypto is legal, how it's taxed and who licenses exchanges, for 14 countries and the EU.US crypto regulationSEC vs. CFTC, the GENIUS Act, the stalled CLARITY Act, Form 1099-DA.EU crypto regulation (MiCA)One licence for the whole EU; the transition ended July 1, 2026.Is crypto banned in China?Exactly what is prohibited, and what isn't.