What is a blockchain?
A blockchain is a shared ledger that thousands of computers keep together. New entries are gathered into blocks, and each block carries a digital fingerprint of the block before it. So the blocks hang together in a chain, and if someone changes an old block, the fingerprint no longer fits. It is the technology behind bitcoin and other cryptocurrencies.
If someone changes an old block, it no longer fits the rest of the chain.
A ledger without a bookkeeper
At a bank, the bank keeps the ledger and you trust the bank. On a blockchain, thousands of computers each hold a copy of the whole ledger. When a new block is added, the network has to agree that it is valid. If one computer tries to cheat, the others reject its copy.
For bitcoin a new block arrives roughly every 10 minutes. Every transaction since January 2009 is in the chain, and anyone can see them — as addresses and amounts, not names.
How the network agrees
- Proof of work (bitcoin): computers called miners spend electricity solving a puzzle. The first to solve it makes the block and gets a reward. It costs a lot of power — and that is exactly what makes cheating expensive.
- Proof of stake (e.g. ethereum since September 2022): instead of electricity, participants put up their own coins as security. If they cheat, they can lose them.
What a blockchain does not do
It does not make a coin valuable. It makes sure the ledger is correct — not that what is written in it is worth anything. And it does not protect you from sending to the wrong address yourself or losing your private key. A transaction on a blockchain usually cannot be undone.
The typical beginner's mistake
Believing that "blockchain" is a quality stamp in itself. Many projects used the word in their marketing and still went to zero. The technology can be solid while the coin is worthless.
How you see it in Kiggo
Kiggo does not show the blockchain itself — Kiggo shows the prices. Under Market → Crypto you see the 25 largest coins (without stablecoins) as a colour map, refreshed every 15 seconds. Tap a tile for three rings (short, medium and long term), "10 years at a glance" and the tax card for your country. Crypto is part of Kiggo Plus.
Related terms
Frequently asked questions
Can anything on a blockchain be changed?
In practice not backwards. To change an old block you would have to redo every block after it and have the majority of the network behind you at the same time. On a large network like bitcoin that is unrealistically expensive. On small networks it has happened.
Is a blockchain anonymous?
Not entirely. All transactions are public and can be followed from address to address. There are no names — but if you buy through a crypto exchange, the exchange knows your name, and the trail can often be linked to you.
Kiggo explains — Kiggo does not advise. We never tell you what to buy or sell, and key figures can only be compared between companies in the same industry. The decision is yours. Last updated 2026-09-23.
Written by Claus Frisch, founder of Kiggo. Not an adviser, not a bank — Kiggo explains, you decide.
