What is Blockchain and How Does It Work?

Imagine a giant ledger – but instead of being held by a bank, it is copied and stored simultaneously on thousands of computers around the world. Each transaction is recorded in a "block," and the blocks link together to form a "chain." No one can alter an old block without breaking the entire chain – that is why blockchain is considered immutable and transparent.
There is no central bank, no central server. If one computer goes offline, thousands of others keep running normally.

What is a Network in Crypto?

Each blockchain is its own network. Bitcoin runs on the Bitcoin network, Ethereum runs on the Ethereum network. There are also BNB Chain, Solana, Polygon, Avalanche, etc. Each network has different speed, transaction fees, and operating mechanisms.

When transferring money, you must choose the correct network. Sending USDT over the BEP-20 network to a wallet that only accepts ERC-20 can cause the funds to be stuck. Not necessarily lost forever, but recovering them is very troublesome and not always successful.

How are Coin, Token, Altcoin, and Stablecoin Different?

Coin vs Token

  • Coin is a currency with its own blockchain, such as BTC (Bitcoin), ETH (Ethereum), SOL (Solana). Coins are often used to pay transaction fees on their own network.
  • Token does not have its own blockchain but is issued based on an existing blockchain (like Ethereum, BNB Chain, Solana, Tron...). For example: UNI and SHIB are tokens running on Ethereum; USDT is a stablecoin but exists as a token on many different networks (ERC-20 on Ethereum, TRC-20 on Tron, BEP-20 on BNB Chain...). In short: coin is the platform, token is what runs on that platform.

How is Bitcoin Different from Ethereum?

  • Bitcoin was created in 2009, primarily as a store of value – often called "digital gold." Its total supply is capped at 21 million coins. Bitcoin's scripting language is quite simple and does not support complex programming.
  • Ethereum was created in 2015 and designed as a programming platform. It is used to run smart contracts, DeFi, NFTs, and decentralized applications (dApps). It is much more flexible but also more complex.

What is a Stablecoin?

Stablecoins are designed so that their price does not fluctuate as wildly as BTC or ETH. The most popular ones are pegged to the USD: USDT (Tether), USDC (USD Coin issued by Circle), DAI (a decentralized stablecoin backed by other crypto). Users often "park" their money in stablecoins during market volatility, without needing to convert to real cash.

What is an Altcoin?

Altcoin is a general term for all coins and tokens that are not Bitcoin – including Ethereum, Solana, Dogecoin, UNI, etc. However, stablecoins (USDT, USDC, DAI) are often treated separately and not called altcoins in everyday conversations. Broad categories include: Layer 1 (platform blockchains like Solana, Avalanche), Layer 2 (run on L1 to speed up and reduce fees like Arbitrum, Polygon), DeFi tokens (UNI, AAVE), meme coins (DOGE, SHIB, PEPE), AI coins (FET, TAO), GameFi/NFT (AXS, IMX).

What is a Smart Contract?

A smart contract is a program that automatically runs on the blockchain when predetermined conditions are met. No intermediary is needed, and once deployed, no one can stop it.

Real-world example: you borrow money on Aave – the smart contract automatically holds the collateral, disburses the loan, and liquidates automatically if the collateral value drops too low. No bank, no staff, no business hours. The combination of applications built on smart contracts forms the DeFi ecosystem (Decentralized Finance).

Crypto Wallets

Classification by Internet Connectivity

  • Hot wallet: always online, convenient for daily use (MetaMask, Trust Wallet, OneKey, etc.).
  • Cold wallet: offline, maximum security (Ledger, Trezor).

Classification by Who Holds the Private Key

  • Custodial wallet: the exchange or a third party holds the key for you (Binance, Coinbase accounts). Convenient but you don't truly own the coins.
  • Non-custodial wallet: you hold the key yourself (MetaMask, Ledger, Trust Wallet, OneKey, etc. all fall into this category).

There are also MPC wallets (key split into multiple fragments) and smart contract wallets (programmable, recoverable, like Safe).

What does "Not your keys, not your coins" mean?

This is the most famous saying in crypto. It means: if you leave your coins on an exchange, you don't truly own them – the exchange does. The exchange can be hacked, go bankrupt, or freeze your account at any time. Only when you hold your own private key (or seed phrase) – are the coins truly yours.

What is BIP-39? How to import a wallet using BIP-39?

  • BIP-39 is the standard that creates a "seed phrase" – a set of 12, 18, or 24 English words used as a full backup of your wallet. Losing your seed phrase means losing your money. Anyone who has your seed phrase has your money.
  • To import a wallet: open your wallet app (MetaMask, Trust Wallet, OneKey...), select "Import wallet" or "Restore wallet," enter the correct order of 12, 18, or 24 words, and the wallet will be restored with its entire balance.

Never enter your seed phrase into a strange website, an app of unknown origin, or share it with anyone – even if they claim to be support from MetaMask or Binance.

Learn about BIP-39 at https://vulehuan.com/en/blog/2026/4/bip39-everything-you-need-to-know-about-the-12-eynC4QuXaEv, generate seed phrases to import into your wallet at https://vulehuan.com/en/tools/seed-vault

When to create a new wallet, when to import?

  • Create a new wallet when you are starting from scratch, want a completely new wallet address, or want to separate assets (e.g., one wallet for daily use, another for long-term holding).
  • Import when you change phones, computers, reinstall an app, or want to use an old wallet on a new device.

Exchanges, Gas Fees, and Market Indicators

How are CEX and DEX different?

  • CEX (centralized exchange) like Binance, Coinbase, OKX – these are real companies, require identity verification (KYC), have high liquidity, and are easy to use. Risks: the exchange can be hacked or go bankrupt, or freeze your account at any time (just like a bank can freeze your account for legal or internal reasons).
  • DEX (decentralized exchange) like Uniswap, PancakeSwap – no company behind them, no KYC required. You connect your wallet and trade directly via smart contracts. Risk: smart contracts may have vulnerabilities that can be exploited.
  • What do wallets like MetaMask, Trust Wallet, OneKey, etc. have to do with this?
    These are non-custodial wallets, not exchanges. They help you hold your own keys and interact directly with DEXs (Uniswap, PancakeSwap) without going through a CEX. You can also send coins from a CEX (Binance) to these wallets to self-custody your assets. Simply put:
    • CEX = bank (they hold your money for you)
    • Wallet (MetaMask, Trust Wallet, OneKey, etc.) = your own personal wallet (you hold it yourself)
    • DEX = decentralized marketplace (you connect your wallet to buy/sell directly)

What is gas fee? Why does it fluctuate?

Gas fee is the payment to computers (nodes) that process transactions on the blockchain. It goes up or down depending on network congestion – like rush hour traffic. On Ethereum, when many people transact at once (NFT drops, big DeFi events...), gas fees can reach tens of dollars for a single small transaction. Networks like Solana or L2s (Arbitrum, Polygon) are often much cheaper.

What are spread, volume, market cap, and liquidity?

  • Spread: the difference between the buy price and the sell price. A small spread usually indicates good liquidity.
  • Volume: total trading value in 24 hours – high volume shows an active market and more reliable trends.
  • Market cap: price multiplied by circulating supply, used to compare the scale between coins.
  • Liquidity: how easily you can buy or sell without moving the price significantly. Low liquidity leads to high slippage.

Meme Coins and Altcoin Season

What is a meme coin? Why are Dogecoin, Shiba Inu, and PEPE popular?

Meme coins have no special technical features – their value comes primarily from community attention, social media virality, and sometimes a tweet from a celebrity. Elon Musk with Dogecoin is a classic example. PEPE rose due to internet culture, SHIB due to its large community and being listed on major exchanges.

Meme coins can multiply 10x, 100x in a few days – but can also lose over 90% in just a few hours. This is the highest-risk area in crypto.

What is altcoin season? How to recognize it?

When Bitcoin has risen strongly and money starts flowing into altcoins, creating a broad price increase – that is "altcoin season." Some signs: Bitcoin dominance (BTC.D) falls below 40–45%, the altcoin index exceeds 75, many mid-cap altcoins rise simultaneously instead of just 1–2 coins, and altcoin trading volume surpasses BTC on major exchanges.

Trading: Spot, Futures, Leverage, and Liquidation

How is Futures different from Spot trading?

  • Spot: you buy real, you receive real. Put in 100 USD to buy BTC, you have 100 USD worth of BTC. Maximum loss equals the amount you put in.
  • Futures: you bet on the price going up (Long) or down (Short) without actually receiving the coin. It allows leverage and carries much higher risk.

What is leverage? Examples x5, x10, x100

Leverage allows you to trade with more money than your actual capital. Example: with 100 USD and x5 leverage, you control 500 USD. BTC rises 10% → you profit 50 USD (50% of your capital), but if BTC falls 10%, you lose 50 USD. With x10, a 10% drop wipes you out. With x100, a 1% move against you triggers immediate liquidation.

What is liquidation? How to avoid it?

When losses reach your margin threshold, the exchange automatically closes your position and you lose all the money you put in – that is liquidation. To avoid it: use low leverage (x2, x3) when starting out, always set a stop-loss before entering a trade, do not put all your capital into one trade, and monitor the liquidation price shown on the exchange.

Over 80% of leveraged traders lose money in the long run. If you are new, practice with spot trading first.

Staking and Airdrop

What is staking? Profit and risks?

Staking is "locking" your coins into the network to help validate transactions, and in return you receive rewards – similar to interest on savings. Returns (APY) typically range from 3–15% depending on the coin. Advantages: passive income, no action needed after staking. Risks: coins are locked for a period of time (lock-up period), you cannot sell during market downturns. New projects offering very high APY are often warning signs.

What is an airdrop? How to receive one?

An airdrop is when a project gives away free coins or tokens to early users or those who complete tasks. Uniswap once gave 400 UNI (worth over 1,000 USD at the time) to everyone who had ever used the app – that is the most famous airdrop in crypto history.

To increase chances of receiving an airdrop: use new DeFi protocols, bridge tokens to a new chain, participate in governance votes, interact regularly with dApps. There is no sure formula, but "use early and use often" is often rewarded.

Never connect your wallet to an airdrop link sent via DM, Telegram, or strange Twitter accounts. This is the most common way to get your wallet drained.

Scams and Safety for Beginners

What are rug pull and honeypot?

  • Rug pull: the project team "pulls the rug" – they pump the price, attract investors, then sell all their tokens and disappear. Liquidity goes to zero within minutes.
  • Honeypot: a more sophisticated trap – the token allows buying, but the smart contract is coded to prevent selling. You see a nice price increase but cannot exit. Funds are stuck forever.

What are FOMO, FUD, REKT, DYOR, HODL?

  • HODL (originated from a misspelled "HOLD" in a BitcoinTalk forum post in 2013): means holding coins for the long term, not selling no matter how the market fluctuates.
  • FOMO (Fear Of Missing Out): the urge to buy quickly when you see a coin rising, often leading to buying at the peak.
  • FUD (Fear, Uncertainty, Doubt): negative news (sometimes deliberate) that causes panic and sell-offs.
  • REKT (slang for "wrecked"): heavy loss, often from liquidation or being scammed.
  • DYOR (Do Your Own Research): a reminder to research for yourself before investing, not blindly trusting anyone's advice.

Sent to wrong address or wrong network – can it be recovered?

  • Wrong address: If the address is not owned by anyone, the money is permanently lost. If the address has an owner, you would need to contact them – but the problem is you don't know who they are because blockchain is anonymous, no contact list or phone number to call. Theoretically you could ask them to send it back, but in practice it's nearly impossible to reach them, and there's no guarantee they would return it.
  • Wrong network – how to handle?
    • Case 1: Sent to your own personal wallet (self-custodial wallet like MetaMask, Trust Wallet, OneKey, etc.): You can still recover it. Just add the correct network to that wallet (or import the seed phrase into a wallet that supports that network). The funds will appear immediately.
    • Case 2: Sent to a wallet that is not yours (someone else's wallet, exchange wallet, contract wallet): Very difficult. If it's an exchange wallet: contact exchange support immediately, it might be recoverable (with a fee).
      If it's a stranger's wallet: nearly impossible to recover because you don't know who they are, blockchain is anonymous, and they have no obligation to return it.

Golden rule: always send a small test amount (2–5 USD) to verify the address and network before sending a large sum.

How to avoid scams?

  • No one gives away free crypto – even if the post looks exactly like Elon Musk or Vitalik.
  • Do not click strange links in DMs, even from people you know (their account may be hacked).
  • Do not install browser extensions from unknown sources.
  • Do not rush – every "only 5 minutes left" deal is a red flag.
  • And always remember: if it sounds too good to be true, it usually is.

What to prepare before buying crypto for the first time?

  • Only invest money you are willing to lose completely – no borrowing, no pledging assets.
  • Choose a reputable exchange with a long history, such as Binance, Coinbase, or OKX. Most importantly: you must prioritize exchanges that are legally permitted to operate in the country where you live. Trading on exchanges that do not comply with local laws can result in blocked withdrawals, frozen accounts, or even administrative or criminal penalties. Research the regulations at the time you start.
  • Complete KYC before depositing funds.
  • Start with Stable Coins (USDT, USDC, etc.), BTC, or ETH rather than buying altcoins or meme coins directly before understanding the basics.
  • Enable two-factor authentication (2FA) on your exchange account immediately.
  • If the amount is large, create a non-custodial wallet (MetaMask, Trust Wallet, OneKey, etc.) to self-custody your coins.
  • Write down your seed phrase and store it physically – do not take photos, do not save to the cloud, do not message it to yourself. Learn about seed phrases at https://vulehuan.com/en/blog/2026/4/bip39-everything-you-need-to-know-about-the-12-eynC4QuXaEv
  • Follow the market but do not trade daily when you are still new.

Crypto is actually not that difficult — but if you don't understand its nature, you can still lose real money. This article https://vulehuan.com/en/blog/2026/4/crypto-security-from-a-to-z-everything-you-need-2kMu5Uq0mI2 gathers questions about crypto security to help you visualize the bigger picture.

You have read this far – that means you are better prepared than most people entering the crypto market. Do your own research (DYOR), start with a small amount, and good luck!

This article is educational and not financial advice. Always do your own research, understand the legal regulations in your country of residence, and consult with professionals before making any decisions regarding digital assets.