Learn crypto from the ground up

What is a blockchain? 3 min read

A blockchain is a shared record book that many computers keep at the same time. Instead of one company holding the master copy, thousands of independent machines each hold an identical one and agree on every new entry.

Entries are grouped into blocks. Each block includes a fingerprint of the one before it, so they form a chain. Changing an old entry would change its fingerprint and break every block after it, which the rest of the network would reject.

That design gives a blockchain three useful properties. It is hard to tamper with, anyone can check it, and no single party can switch it off. The trade-off is that it is slower and more expensive than a normal database, so it only makes sense where trust between strangers is the problem being solved.

A coin such as bitcoin is simply an entry in that record. When you 'send' it, the network updates the record to show a new owner.

Wallets and keys 4 min read

A crypto wallet does not hold coins. The coins live on the blockchain. A wallet holds keys, and keys are what prove you are allowed to move them.

Each wallet has a public address, which is safe to share so people can pay you, and a private key, which must stay secret. Most wallets represent the private key as a seed phrase of 12 or 24 ordinary words.

Whoever has the seed phrase controls the money. There is no password reset and no helpline. Write it on paper, keep it offline, and never type it into a website or send it to anyone.

A custodial wallet, such as an exchange account, means a company holds the keys for you. That is convenient, but you are trusting the company. A self-custody wallet means you hold the keys. A hardware wallet is a small device that keeps keys offline and is the usual choice for larger amounts.

Proof of work vs proof of stake 4 min read

Every blockchain needs a way to decide who adds the next block and to make cheating expensive. The two main answers are proof of work and proof of stake.

In proof of work, computers called miners race to solve a puzzle that takes real electricity. The winner adds the block and earns new coins. Attacking the network would mean out-spending all honest miners combined. Bitcoin, Monero, Zcash, Litecoin and Kaspa work this way.

In proof of stake, participants called validators lock up coins as a deposit. They take turns proposing blocks and earn rewards, and can lose part of the deposit if they cheat. It uses far less energy. Ethereum, Solana, Cardano, Sui, NEAR and Gram work this way.

Neither is simply better. Proof of work ties security to physical cost and has the longest track record. Proof of stake is more efficient and usually faster, but gives more influence to those who already hold the most coins.

Stablecoins 3 min read

A stablecoin is a token designed to hold a steady value, almost always one US dollar. Stablecoins let people move dollars on a blockchain at any hour without a bank transfer.

Fiat-backed stablecoins such as USDT and USDC are issued by a company that holds cash and short-term government debt in reserve. You are trusting that company and its reserves.

Crypto-backed stablecoins such as DAI and USDS are created by locking up more collateral than the dollars issued, with rules enforced by smart contracts.

Synthetic dollars such as Ethena's USDe hold crypto and an equal bet against it, so the two cancel out. They can pay a yield, but that yield is variable and comes with extra risks.

No stablecoin is a bank deposit. None is covered by deposit insurance, and several have lost their peg in the past, some briefly and some permanently.

DeFi 3 min read

DeFi is short for decentralised finance: financial services run by smart contracts instead of banks or brokers. You connect a wallet and interact with the code directly.

The main building blocks are decentralised exchanges such as Uniswap, where you swap tokens against pooled funds; lending markets such as Aave and Morpho, where you deposit to earn interest or borrow against collateral; and derivatives venues such as Hyperliquid.

The appeal is open access and transparency: anyone can use it, and anyone can inspect the rules. The risks are just as real. Code can have bugs, collateral can be liquidated in a sudden drop, and there is nobody to call if you make a mistake.

A useful question for any DeFi yield is: where does the money come from? If you cannot explain the source, treat the yield as a warning.

Oracles 2 min read

A blockchain can only see its own data. It has no idea what a dollar is worth, who won an election or whether a shipment arrived. An oracle is a service that brings outside information on-chain.

This matters more than it sounds. A lending app that holds billions needs an accurate price to decide when to liquidate a loan. If the price feed is wrong or manipulated, the app can be drained.

Oracle networks reduce that risk by having many independent operators fetch the data from many sources and combining their answers. Chainlink is the most widely used. Newer services also carry messages and tokens between chains, a job known as interoperability.

Privacy tech 4 min read

Most blockchains are public. Anyone can look up an address and see every payment it has ever made. Privacy technology tries to keep the benefits of a shared ledger without exposing everyone's finances.

Ring signatures and stealth addresses, used by Monero, hide the true sender among decoys and give every payment a one-time destination. Privacy is always on.

Zero-knowledge proofs, used by Zcash and Midnight, let you prove a statement is true without revealing why. A shielded Zcash payment proves that the sender has the funds without showing the sender, receiver or amount.

Selective disclosure lets users reveal specific facts to specific parties, for example proving you are over 18 without showing your birthday. Midnight is built around this idea.

Need-to-know ledgers, used by Canton, send each party only the part of a transaction that involves them, which suits banks with legal confidentiality duties.

Privacy is legal and useful, but regulators treat anonymous coins cautiously. Some exchanges have delisted them, and EU rules applying from July 2027 restrict how regulated firms can handle them.

Tokenised assets (RWA) 3 min read

RWA stands for real-world assets. Tokenisation means representing something that already exists in traditional finance, such as a government bond, a money market fund or a bank deposit, as a token on a blockchain.

The pitch is efficiency. Tokens can settle in seconds rather than days, trade around the clock, and be used as collateral by software. Large asset managers and banks now run live products, with tokenised US Treasuries the biggest category so far.

The token is only as good as the legal claim behind it. Someone off-chain still holds the real asset, and the rules about who may buy are often strict.

Different projects attack different parts of the problem: Ondo issues tokenised funds, Canton provides a privacy-preserving network for institutions, Quant connects bank systems to ledgers, and Chainlink supplies data and cross-chain messaging.

Crypto ETFs 3 min read

An exchange-traded fund (ETF) is a fund whose shares trade on a stock exchange. A spot crypto ETF holds the actual coin, so its share price tracks the coin's price, minus fees.

ETFs let people get exposure through an ordinary brokerage or retirement account without handling wallets or keys. US spot bitcoin ETFs began trading in January 2024 and spot ether ETFs followed in July 2024. Since late 2025, US funds have launched for further coins, including Litecoin, Hedera, Sui, Hyperliquid and Zcash.

Owning an ETF share is not the same as owning the coin. You cannot send it to a wallet or spend it, you pay a yearly fee, and it trades only during market hours.

An ETF approval says a product meets listing rules. It is not a judgement that the underlying coin is a good investment.

How to stay safe: a scam checklist 4 min read

Most people who lose money in crypto are not hacked by brilliant code. They are tricked. These rules stop the great majority of scams.

• Never share your seed phrase. No real support agent, wallet or website will ever ask for it.
• Nobody gives away free money. 'Send 1, get 2 back' is always theft, whoever appears to be promoting it.
• Be suspicious of urgency. 'Act now or lose your funds' is pressure designed to stop you thinking.
• You never need to 'migrate' or 'claim' after a rename. When Toncoin became Gram in June 2026, holders had to do nothing. Sites asking you to connect a wallet to swap were scams.
• Check the address bar. Fake sites copy real ones exactly. Use bookmarks, not search ads.
• Check the token. Copycat tokens reuse famous names. Confirm the contract address from the project's official site.
• Guaranteed returns do not exist. A promised daily or weekly profit is the classic sign of a Ponzi scheme.
• Strangers who become friends, then mention investing, are running a script. This is the most costly scam of all.
• Send a small test first when using a new address. Transactions cannot be reversed.
• Use a hardware wallet for amounts you could not afford to lose, and keep the backup on paper.

If something has already gone wrong, do not pay a 'recovery service' that contacts you. That is usually the same scammers returning for a second round.