The learning path
A bridge moves value between blockchains, either by locking an asset on one chain and minting a representation on another, or by using liquidity pools on both sides. Bridges have been the largest single source of losses in crypto, with individual hacks exceeding hundreds of millions of dollars, so use official bridges, move in small amounts and check the destination network before confirming.
Why bridges exist
Blockchains cannot see each other. Ethereum has no idea what happens on Solana. There is no built in way to send an asset from one to the other, because from Ethereum's perspective Solana does not exist.
A bridge is the workaround, and every design involves trusting something.
The two designs
| Type | How it works | What you are trusting |
|---|---|---|
| Lock and mint | The asset is locked on the source chain and a representation is minted on the destination | Whoever holds the locked collateral, and the contract holding it |
| Liquidity pool | Pools exist on both chains. You deposit on one side and receive from the pool on the other | The pool operators and the messaging layer between chains |
A third approach avoids the problem. THORChain settles natively on each chain, so you send real BTC and receive real ETH with no wrapped token in between. It is slower and the design is harder, but it removes the wrapped asset risk entirely.
Why bridges get hacked
A bridge holds all the locked collateral in one place. That makes it the largest, most concentrated pot of money in crypto, and it is defended by code that has to be perfect across two different chains at once.
The result is a long list of nine figure losses. Ronin, Wormhole, Nomad and Harmony all lost hundreds of millions. This is not ancient history and the structural reason has not gone away.
Bridging safely
Use the official bridge for the destination chain
Base, Arbitrum, Optimism and every major layer 2 run their own. They are slower than third party options and considerably safer.
Check both networks before confirming
Confirm the source and destination are what you intend. This is where most user errors happen.
Send a small test first
Always. Bridge twenty dollars, confirm arrival, then send the rest. The extra fee is trivial insurance.
Understand the waiting period
Withdrawing from an optimistic rollup through the official bridge takes about seven days by design. Third party bridges offer instant exits for a fee by fronting you the liquidity.
Keep gas on the destination
Arriving on a new chain with tokens and no native token to pay fees is a common and frustrating trap.
When you can skip bridging entirely
Often you do not need a bridge at all:
- Withdraw directly from an exchange. Coinbase and Binance.US let you withdraw straight to Base, Arbitrum, Solana and more. No bridge involved.
- Use a cross chain aggregator that routes through the safest available path and shows you which bridge it is using.
- Just use the chain you are already on. Most beginners bridge because they think they need to, not because they do.
Common questions
What is a wrapped token?
A token on one chain representing an asset held on another. WBTC on Ethereum represents real BTC held by a custodian. It trades like BTC and carries the custodian risk on top.
Why does withdrawing from Arbitrum take seven days?
Optimistic rollups assume transactions are valid and allow a challenge window for anyone to prove otherwise. That window is the seven days. Third party bridges skip it by fronting you funds.
Are bridges getting safer?
Somewhat. Designs have improved and the largest bridges are heavily audited. The structural problem of concentrated value defended by complex cross chain code has not been solved.
Where to go next
Stuck on this one?
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