Cross-chain Bridges
A bridge lets you move an asset from one blockchain to another, typically by locking it on the source chain and minting a wrapped version on the destination.
In depth
Chains cannot talk to each other natively, so bridges act as escrow agents. Your BTC is locked in a vault and an equivalent token is issued on Ethereum; burning that token unlocks the BTC. Bridges hold large pooled balances, which has made them prime targets for hacks.
Why it matters
Bridged assets carry extra counterparty risk — worth knowing before you trust a wrapped token.