Crypto Infrastructure
Nothing crosses the bridge. Only a claim does.
Blockchains are separate networks — a token on Ethereum is not simply usable on Solana. A bridge does not carry the asset across. It locks the original where it is and issues a representative version on the other side.
The problem
Send one asset to the other chain. Then bring it home.
Walk the full round trip, one press at a time. Keep one eye on the counter in the corner — the whole lesson is in the number that never changes.
One asset, two chains
Source chain
Target chain
Lock, mint, burn, release. That cycle is the whole mechanism, and it exists to guarantee one thing: the representative version is always backed by a real, locked original, so nothing is ever spent twice. The version on the target chain is often called a wrapped token — a representative of an original held on another chain. It is a claim, not a second copy of the asset. Its worth depends entirely on the original being correctly locked and the swap back working reliably.
Every round trip anyone runs leaves one more locked original in the same place.
A bridge is not holding your original. It is holding everyone's. To back every representative it has ever minted, the locked originals sit together in one place — and at the same time the bridge joins several technical systems to each other. Large amounts of concentrated capital plus several connected systems adds up to a large attack surface, and that is precisely what makes bridges attractive targets. It is a structural property of the design, not bad luck: it is why bridges count among the riskiest parts of crypto infrastructure, and why using one means judging the security of the bridge itself, not only of the chain you are heading for.
The definition
Three things the round trip just showed you.
Tap each card for what it means.
Hands on
Who actually performs the lock and the mint?
There are two basic types. Switch between them and read the same three rows on each.
Neither column is the safe one. Each type simply relocates the assumption you are making — toward an entity, or toward code. No bridge is entirely free of risk, and a decentralised one is no exception.
The bridge
Four things to carry out of this lesson.
Why the connection exists, how it is made, and what the model piles up.
Bridges connect separate ecosystems through wrapped tokens — sometimes through a central entity, sometimes through smart contracts, but never without assumptions. The next lesson stops crossing between ecosystems and stays inside one, asking a different question: how do you make a single chain carry more without leaving it? That is Layer 2.
Check yourself
Five questions.
Answers come straight from this lesson. Submitting completes it.