What is a blockchain?
DefinitionA blockchain is a shared digital ledger, copied across many independent computers, that records transactions in blocks linked by cryptographic hashes, so past entries can’t be quietly changed and no single company controls the record.
How a blockchain works
A blockchain works by grouping new transactions into blocks and chaining each block to the one before it. Every block contains a hash, a short cryptographic fingerprint, of the previous block. Change one old transaction and its fingerprint changes, which breaks every block after it, so tampering is obvious to everyone.
Thousands of computers, called nodes, keep their own copy of the chain and check every new block against the same rules. No bank sits in the middle approving payments; the network as a whole agrees on what happened.
How the network agrees: consensus
Consensus is the method a blockchain uses to decide who adds the next block and which version of history is valid. The two common methods are:
- Proof of work: miners spend computing power to win the right to add a block. Bitcoin, Litecoin and Dogecoin work this way.
- Proof of stake: validators lock up the network’s coin as a deposit and can lose part of it if they cheat. Ethereum (since September 2022), TON and many newer chains work this way.
An everyday example: sending USDT
Sending USDT on Tron shows a blockchain at work. Your wallet signs a transaction and broadcasts it, a validator puts it in a block, other nodes verify it, and within seconds it is part of the shared record. Anyone can look it up on a block explorer by its transaction ID.
Each blockchain is a separate network, so USDT on Tron and USDT on TON live on different chains and the sender and receiver must use the same one. Waletifi supports 15 networks, from Bitcoin and Ethereum to TON, Tron and Solana, and shows the network on every receive address and on the review screen.
What a blockchain does not do
A blockchain guarantees that the record is consistent, not that a transaction was a good idea. Keep its limits in mind:
- Transactions are final: no bank can reverse a payment sent to the wrong address or to a scammer.
- Most blockchains are public: amounts and addresses are visible to anyone, even if names are not.
- Whoever holds the private key controls the funds, so keeping your keys safe is your job.
- Fees and speed differ by network and change with demand.
