Knowledge quiz

There is no central authority. Every full node checks each block against the consensus rules and rejects blocks that break them – even if a big miner produced them. Satoshi Nakamoto withdrew in 2011.

1 BTC = 100,000,000 sats. So you don’t need to buy a whole bitcoin: $1 currently gets you about 1,159 sats.

The block reward started at 50 BTC and halves every 210,000 blocks. Added up, that is just under 21 million (20,999,999.9769 BTC); the last fractions arrive around 2140. Issued so far: 20,093,853 BTC, or 95.69%.

Every 210,000 blocks, roughly every four years, the amount of new bitcoin per block halves – most recently on 20 April 2024, from 6.25 to 3.125 BTC. At the current pace, the next halving at block 1,050,000 arrives around April 2028. Existing bitcoin are unaffected.

The target is 10 minutes. To keep it there, the network adjusts the mining difficulty to the computing power every 2,016 blocks – roughly every two weeks.

A full node downloads every block and checks each transaction against the rules itself – “don’t trust, verify”. Anyone can run one, for example on a small computer at home.

Lightning builds payment channels on top of Bitcoin. Many small payments run through them almost instantly and very cheaply. For long-term saving, the blockchain itself remains the standard.

There is no authority that can claw payments back. So check the receiving address carefully and send a small test amount the first time.

The genesis block contains that day’s headline from the London Times: “Chancellor on brink of second bailout for banks”. It proves the block was not created earlier – and is often read as a comment on the financial crisis.

The largest falls from a record high (daily close in US dollars): 2013–2015 −85%, 2017/18 −83%, 2021/22 −77%. After the record high on 6 October 2025, the price was at times 53% lower. Anyone investing must expect such crashes.

Check for yourself: TradingView ↗ · CoinGecko ↗

With a spread you buy slightly above the market price. The mark-up is built into the price and easily overlooked – so compare how much bitcoin you end up with for your money.

Since 1 July 2026 all transition periods have ended: anyone offering crypto services in the EU needs MiCA authorisation. You can check it in the ESMA register or with BaFin. Guaranteed returns and celebrity adverts, by contrast, are typical warning signs of fraud.

If the test amount arrives, address and wallet are right. Copying addresses from the history is risky: scammers plant look-alike addresses there. Above a value of €1,000, EU law also requires the provider to check that the wallet is yours.

With a provider you have a balance – a claim against it, not bitcoin of your own. After the collapses of Mt. Gox (2014) and FTX (2022), customers waited for years; FTX paid out dollars instead of bitcoin. With your own keys, you carry the responsibility for backups yourself.

The seed phrase is the master key to your bitcoin. Stored digitally, it can be stolen through malware or hacked accounts. Best written by hand, on metal for the long term, with at least two copies in separate places.

Anyone asking for your seed phrase wants to rob you – without exception, whether by email, call, chat or form. Contact support yourself, via the official app or website.

Foundation first: a reserve of about three to six months’ expenses and no expensive debt such as an overdraft. Don’t buy on credit or with leverage – crashes hit such positions first and hardest.

A savings plan buys regularly for a fixed amount, whatever the price. That does not guarantee more profit: for equities, Vanguard found an immediate lump sum ahead in about two out of three cases. Its advantage: it suits a regular income and helps against gut decisions.

Gains are taxable if no more than one year lies between purchase and sale (§ 23 EStG). The purchase day does not count and the period ends at the end of 15 March 2026 – so a sale is tax-free from 16 March 2026. The government plans to scrap the holding period for purchases from 2027; it is not law yet (as of September 2026).

The €1,000 is an exemption limit, not an allowance: the gain stays tax-free only if it totals less than €1,000 for the year. At €999.99 you pay nothing; at €1,000 the whole amount is taxed at your personal rate.