What is Bridging in Crypto?

Summary: Bridging moves value between blockchains that cannot talk to each other. Nothing actually crosses: the bridge locks or burns your asset on the first chain and issues a matching token on the second. That design is why bridges have been the single most profitable target in crypto for attackers.

• Your original coin never moves. You receive a claim on it, issued on the other chain.
• Wrapped tokens are only worth as much as the bridge backing them remains solvent and honest.
• Bridge exploits have produced several of the largest single thefts in crypto history.
• Many reasons people bridge can be avoided entirely by spending the asset where it already is.

Blockchains are separate systems with no native way to verify each other's state. Bitcoin does not know what happened on Ethereum, and Ethereum cannot read Solana. A bridge is the workaround: a piece of infrastructure that watches one chain, and tells another chain what it saw.

That sentence contains the whole risk. Everything downstream depends on the second chain trusting the message, and on the message being true.

What a Bridge Actually Does

The common design is lock-and-mint. You send your asset to a contract on the source chain, where it is locked. The bridge observes that deposit and mints an equivalent wrapped token on the destination chain. To come back, you burn the wrapped token and the original is released. Our explainer on what a blockchain is covers why chains cannot simply verify each other directly.

So the wrapped token in your wallet is an IOU. It holds its value because the locked collateral exists and the bridge will honour redemptions. If either stops being true, the wrapped token can trade to nothing while the asset it represents is still sitting in a contract, or gone.

Why You Would Bridge Anything

• Cheaper transactions. Moving to a chain with lower fees is the most common reason, and often the best one - see what is a gas fee.
• Access to an application that only exists on one chain. A platform like Sorare, which issues its collectibles on-chain, is only reachable if your funds are sitting on the network it uses.
• Getting a stablecoin onto the network where you need to spend it. Note that USDT and USDC are issued natively on many chains, which usually removes the need to bridge them at all.

The third case is worth pausing on, because it is where most unnecessary bridging happens. If a stablecoin exists natively on your destination chain, buying or withdrawing it there directly avoids the bridge and its risk entirely.

Why Bridges Are the Most Attacked Part of Crypto

Bridges concentrate collateral from multiple chains behind a single verification step, which makes them worth more to break than almost anything else in the ecosystem. The historical record is stark: the Ronin bridge lost around 624 million dollars in March 2022, Wormhole around 320 million a month earlier, and Nomad around 190 million that August. Security firm Hacken's overview of cross-chain bridge security walks through how the individual attack types work.

What is uncomfortable is that most of these were not broken cryptography. Attackers forged a deposit the bridge believed, or obtained enough validator signatures to authorise a transfer that looked entirely valid from the inside. Audits check whether the code does what it says. They do not check whether what it says is enough.

Trusted vs Trustless Bridges

A trusted bridge relies on a named set of validators or a company holding the collateral. You are trusting people, in much the way you trust an exchange - our explainer on custodial versus non-custodial wallets covers that trade-off in general terms. A trustless bridge tries to replace those people with cryptographic proofs verified on-chain.

Trustless is better in principle and harder to build, and the label is applied loosely. The practical question is not which word the project uses but how many independent parties would have to fail or collude for your funds to move without your say. If that number is one, treat the bridge as a custodian.

How to Bridge Without Losing Money

• Use the chain's official bridge where one exists, rather than a third-party bridge offering better rates.
• Send a small test amount first and confirm it arrives before moving the rest - the same discipline as any transfer between wallets.
• Check you are on the real site. Bridge front-ends are a standing phishing target, and a cloned interface will happily take a real deposit.
• Do not leave value parked in wrapped tokens longer than you need to. Unwrap once you are done.

Avoid signing bridge transactions on networks you do not control. On shared or public wifi, DNS tampering gives an attacker a way to put a cloned front-end in front of you, and a bridge approval is not something you can reverse once it is signed.

When You Do Not Need to Bridge at All

A lot of bridging happens because someone wants to convert an asset into something spendable and assumes they have to consolidate it onto one chain first. Often they do not. Buying a gift card directly from the chain the asset already sits on skips the bridge, the wrapped token and the risk, and our guide to buying gift cards with crypto covers how that works. For Bitcoin specifically, paying over Lightning is cheaper than moving it anywhere else first.

When Bridging Is Worth the Risk

Bridging is worth it when you need to be on a specific chain for a specific reason, for a short period, with an amount you have thought about losing. It is not worth it as a routine way to shuffle holdings around, and it is rarely worth it just to make an asset spendable. If that is the goal, browse what you can buy with crypto directly and leave the coin on the chain it is already on.