Crypto basics: the key ideas explained in plain English

What is cryptocurrency?

Cryptocurrency is digital money secured by cryptography and recorded on a blockchain, a shared ledger maintained by a decentralised network rather than a bank or government. Bitcoin was the first, launched in 2009; there are now thousands of others. Because no central party controls the ledger, crypto can be sent person-to-person anywhere, any time, without a bank in the middle, and the supply of many coins is fixed by code rather than set by a central bank.

In Australia, you buy and hold cryptocurrency through AUSTRAC-registered exchanges, and it is legal and widely used. It is also volatile and largely speculative: prices swing hard, there is no central authority to reverse a mistaken or fraudulent transaction, and most of the consumer protections that apply to bank deposits do not apply. Treat it as a high-risk asset, only invest what you can afford to lose, and remember the ATO taxes most crypto gains.

What is blockchain?

A blockchain is a shared digital ledger that records transactions in batches called blocks, each cryptographically linked to the one before it, and maintained across a decentralised network of computers. Because every block contains a fingerprint (a hash) of the previous block, changing any past record would break the chain and be instantly detectable. That is what makes a blockchain tamper-evident and removes the need for a single trusted middleman like a bank.

Blockchain is the technology underneath Bitcoin and other cryptocurrencies, but the idea is broader: any record that benefits from being shared, permanent and hard to falsify can use one. Its strengths are transparency, security through decentralisation, and resistance to tampering. Its trade-offs are speed and scale, since thousands of computers agreeing on every update is slower than a single database. Understanding the blockchain is the foundation for understanding crypto.

How does Bitcoin work?

Bitcoin works as a shared, public record of transactions, the blockchain, maintained by thousands of computers worldwide rather than a bank. When you send Bitcoin, your transaction is broadcast to the network, bundled into a block, verified by miners who compete using computing power, and then permanently recorded on the blockchain that everyone can see. No central authority is needed, and no one can quietly change the record.

Ownership is controlled by cryptographic keys: a public address others can send to, and a private key only you hold that authorises spending. Mining both secures the network and releases new coins on a fixed schedule, with the reward halving every four years up to a hard cap of 21 million. The result is digital money that is decentralised, transparent and very hard to counterfeit, though the price is volatile and you are responsible for keeping your keys safe.

What is a satoshi?

A satoshi (or "sat") is the smallest unit of Bitcoin: one hundred-millionth of a single Bitcoin, or 0.00000001 BTC. Just as a dollar divides into 100 cents, one Bitcoin divides into 100,000,000 satoshis. The unit is named after Bitcoin's pseudonymous creator, Satoshi Nakamoto.

Satoshis matter because a whole Bitcoin is expensive, so most real activity happens in sats. They let you buy, send and think about Bitcoin in small, everyday amounts, which is why the phrase "stacking sats" describes steadily accumulating Bitcoin a little at a time. Use the converter on this page to switch between satoshis, BTC and Australian or US dollars at the live price.

What is the Bitcoin halving?

The Bitcoin halving is a scheduled event, roughly every four years, where the reward paid to miners for adding a new block is cut in half. It is how Bitcoin slows the creation of new coins over time, building in a predictable, shrinking supply until the cap of 21 million is reached around the year 2140. The reward started at 50 BTC per block in 2009 and, after four halvings, sits at 3.125 BTC since April 2024.

The halving matters because it cuts the flow of new Bitcoin in half overnight, and historically the largest price cycles have followed in the year or so after each one. That pattern is widely watched but not guaranteed, and past cycles are not a promise about future ones. The halving is fixed in Bitcoin's code, so it happens automatically and on schedule, with no committee or company able to change it.

Proof of work vs proof of stake

Proof of work and proof of stake are the two main ways a blockchain agrees on which transactions are valid without a central authority. Proof of work, used by Bitcoin, has computers (miners) compete to solve hard puzzles using real electricity; the winner adds the next block and earns the reward. Proof of stake, used by Ethereum since 2022, has participants (validators) lock up coins as collateral and be chosen to add blocks, with no puzzle-solving.

The core trade-off is energy versus design simplicity. Proof of work is battle-tested and secured by physical cost, but uses a lot of electricity. Proof of stake uses over 99 percent less energy and allows faster, cheaper networks, but is newer and concentrates influence among those who hold the most coins. Neither is simply "better"; they make different trade-offs, which is why Bitcoin and Ethereum each chose differently.

What is the Bitcoin Lightning Network?

The Lightning Network is a "layer 2" built on top of Bitcoin that lets people send Bitcoin payments instantly and for almost no fee. The main Bitcoin blockchain is secure but slow and can get expensive when busy, which makes it impractical for small, everyday payments like buying a coffee. Lightning fixes that by moving most transactions off the main chain into fast payment channels, settling back to the blockchain only when needed.

It works through payment channels: two parties lock some Bitcoin into a shared channel and can then send funds back and forth instantly, with only the opening and closing recorded on the main blockchain. Channels connect into a network, so you can pay someone you have no direct channel with by routing through others. The trade-off is added complexity and the need for online, funded channels, but for fast, cheap, small Bitcoin payments it is the leading solution.

What is Ethereum?

Ethereum is a programmable blockchain, a global computer that runs apps and agreements without a central operator. Where Bitcoin was built mainly to move and store value, Ethereum was built to run code, called smart contracts, that executes automatically. Its native cryptocurrency, Ether (ETH), is used to pay the fees that power the network and is the second-largest crypto by value.

Most of the crypto world is built on Ethereum: stablecoins, decentralised finance, NFTs and thousands of tokens all run on it. Every action costs a fee, paid in ETH and known as gas. Ethereum is more flexible than Bitcoin but also more complex, and that complexity brings extra risks, from smart-contract bugs to volatile gas fees. ETH is a volatile asset and selling it in Australia is generally a taxable event.

What is a smart contract?

A smart contract is a program stored on a blockchain that runs automatically when its conditions are met, with no middleman needed to enforce it. Think of it as an "if this, then that" agreement written in code: if the payment arrives, then the asset is released, automatically and exactly as written. Because it lives on a blockchain, no single party can alter it or stop it once deployed.

Smart contracts are the engine behind most of what crypto can do beyond simple payments: decentralised finance, NFTs, stablecoins and tokens all rely on them. The benefit is automation without trusting a central operator. The risk is that code can contain bugs, and a flawed or malicious contract can lose user funds with no one to reverse the transaction. The phrase is most associated with Ethereum, which made smart contracts its core feature.

What is DeFi (decentralised finance)?

DeFi, or decentralised finance, is financial services like lending, borrowing, trading and earning yield, run by code (smart contracts) on a blockchain instead of by banks or brokers. There is no company in the middle: the rules are written into self-executing contracts, mostly on Ethereum, and anyone with a wallet can use them directly. It aims to recreate the financial system in an open, permissionless form where you keep custody of your own assets.

The appeal is access and control: no gatekeepers, 24/7 markets, and you hold your own funds. The trade-off is that there is no safety net. Smart-contract bugs, hacks, scams and the absence of any regulator or insurance make DeFi genuinely high-risk, and "yields" that look too good usually are. In Australia, DeFi activity is also taxable and the record-keeping is complex. Treat DeFi as the experimental, high-risk frontier of crypto, not a substitute for a bank.

What is a stablecoin?

A stablecoin is a cryptocurrency designed to hold a steady value, almost always pegged to a stable asset like the US dollar, so one coin is worth about US$1. It combines the speed and borderless transfer of crypto with the price stability of regular money. Stablecoins like USDT and USDC are the main way traders park funds, move money between exchanges, and access decentralised finance without converting back to cash.

How well a stablecoin holds its peg depends entirely on what backs it. The safest are fully backed by real cash and short-term government debt held in reserve, so each coin can be redeemed for a real dollar. Riskier designs rely on other crypto or on algorithms, and these have failed dramatically before, most infamously when TerraUSD collapsed to near zero in 2022. A stablecoin is only as stable as its backing, so the type matters enormously.

What is an NFT?

An NFT, or non-fungible token, is a unique token on a blockchain that proves ownership of a specific digital (or sometimes physical) item. "Non-fungible" means each one is one-of-a-kind and not interchangeable, unlike a currency where every unit is identical. NFTs became famous for digital art and collectibles, where the token records who owns a particular item even if the image itself can be copied.

The honest picture in 2026: the speculative NFT boom of 2021-22 collapsed, and most NFTs from that era are now worth a fraction of their peak or nothing. The underlying technology, a verifiable record of unique ownership, has real potential uses (tickets, memberships, in-game items, certificates), but as an investment NFTs are extremely speculative and illiquid. In Australia they are also a capital-gains-tax asset, so buying, selling and creating them has tax consequences.

What is Web3?

Web3 is the idea of a next phase of the internet built on blockchains, where users own their data, money and digital assets directly, rather than relying on big platforms that own and monetise them. The shorthand is "read, write, own": Web1 was read-only pages, Web2 added user-created content but on platforms that own it, and Web3 aims to add ownership through crypto, wallets and decentralised apps.

The vision is an internet without gatekeepers, where you control your identity and assets via a crypto wallet. The honest reality in 2026 is that Web3 is still early, fragmented and far from mainstream: much of it is speculative, the user experience is hard, and plenty of "Web3" branding is marketing on top of ordinary products. The underlying technologies, blockchains, tokens and self-custody, are real and useful, but Web3 as a finished, mass-adopted internet does not exist yet.

What is a meme coin?

A meme coin is a cryptocurrency inspired by a joke, internet meme, animal or online community, usually with little or no underlying use beyond speculation. Dogecoin and Shiba Inu are the best-known examples. Their value comes almost entirely from hype, social-media attention and community enthusiasm rather than technology or cash flow.

Meme coins can post enormous, rapid gains, which is what draws people in, but they are among the riskiest assets in crypto. Most go to zero, prices are heavily driven by hype and influential figures, and the space is full of scams, including "pump and dump" schemes and "rug pulls" where creators vanish with the money. Treat any meme coin as money you are fully prepared to lose, never as an investment with a floor under it. This is general information, not financial advice.

What is a crypto exchange?

A crypto exchange is an online platform where you buy, sell and trade cryptocurrency, usually funding with regular money like Australian dollars. It is the main on-ramp from cash into crypto and back. Most people use a centralised exchange, which works much like a stockbroking app: you create an account, deposit AUD via PayID or bank transfer, and buy coins at the market price.

There are two broad types. Centralised exchanges (like Binance, CoinSpot or Independent Reserve) are run by a company that holds your funds and handles the trading; they are easy to use but you trust the operator with custody. Decentralised exchanges let you trade directly from your own wallet via smart contracts, with no company holding your coins, but they are more complex. In Australia, any exchange serving residents should be registered with AUSTRAC, and selling crypto is generally a taxable event.

What is a crypto wallet?

A crypto wallet does not actually hold your coins; it stores the cryptographic keys that prove ownership and let you spend them. Your public key is like an account number you share to receive crypto; your private key is the secret that controls the funds and must never be shared. The coins themselves always live on the blockchain. Whoever holds the private key controls the crypto, which is the single most important idea in crypto security.

Wallets come in two main splits. Hot wallets are connected to the internet (convenient, less secure); cold wallets are offline (more secure, less convenient). And custodial wallets mean an exchange holds your keys for you, while self-custody means you hold them yourself. The phrase "not your keys, not your coins" captures the trade-off: self-custody gives you full control but full responsibility, including safeguarding a recovery seed phrase that, if lost or stolen, means the crypto is gone for good.

What is staking in crypto?

Staking is locking up a proof-of-stake cryptocurrency to help run and secure its network, and earning rewards in return, a bit like earning interest for putting your coins to work. Proof-of-stake networks like Ethereum choose who validates transactions based on how much is staked, and reward stakers with new coins. You can stake directly, through a staking pool, or simply via an exchange that offers staking on your behalf.

The rewards are not free money. Staked coins are often locked for a period and cannot be sold, so a price drop while locked can wipe out the rewards and more. Some networks can penalise (slash) misbehaving validators, and exchange staking adds counterparty risk. In Australia, staking rewards are generally taxed as ordinary income at the value when received, and disposing of the coins later is a separate capital-gains event, so the tax treatment is two-layered and worth understanding before you start.

What is dollar cost averaging?

Dollar cost averaging (DCA) is investing a fixed amount of money at regular intervals, regardless of the price, instead of trying to time the market. You might buy $100 of an asset every week or month, come rain or shine. When the price is low your fixed amount buys more units, and when it is high it buys fewer, so your average entry price is smoothed out over time.

The appeal is that it removes the pressure and guesswork of timing, enforces a disciplined habit, and softens the emotional sting of volatility, which is why it is so popular for volatile assets like Bitcoin. The trade-off: over the long run, investing a lump sum upfront has historically beaten DCA more often than not, simply because markets tend to rise over time. DCA is a risk-management and behaviour tool, not a profit-maximising one, and it does not protect you from losses in a sustained downtrend.

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