What is blockchain?
Shared ledgers, on-chain transfers, and where online exchangers fit.
Blockchain is a shared ledger: many computers keep the same ordered history of transactions, and new entries are appended in blocks that reference previous ones.
That design makes it hard to rewrite the past without controlling most of the network. Public chains like Bitcoin and Ethereum use this idea so strangers can transfer value without a single central database operator.
Why exchangers still matter
A blockchain moves crypto between addresses. Most people still need an on-ramp or off-ramp to bank cards, local payment rails, or cash. Online exchangers sit in that gap — and OnExchanger compares their live offers so you can see how much you receive before you leave to a partner.
Practical takeaway
When you compare BTC, USDT, or other assets on OnExchanger, you are comparing partner quotes that settle on-chain or to fiat rails after you complete the deal on their site. Always check network (for example TRC-20 vs ERC-20), limits, and the receive amount with fees included when the feed allows it.