Bridges & Oracles

Why blockchains need to connect

Each blockchain is its own separate ledger with its own rules, validators and coin. Bitcoin's ledger has no idea what happened on Ethereum, and Ethereum's ledger has no idea what happened on Solana. But users often want to move value or information between them — for example, spending a stablecoin that was issued on Ethereum while using an app on a cheaper network. Bridges and oracles are the tools that make this possible without merging the chains themselves.

How a bridge moves value across chains

A bridge does not physically move coins from one chain to another — no transaction can cross a blockchain's boundary. Instead, a bridge locks (or burns) the asset on the source chain and mints an equivalent representation on the destination chain, using a set of validators, a multisig, or a smart-contract mechanism to agree that the lock actually happened. Reversing the trip burns the representation on the destination chain and unlocks (or re-mints) the original asset back on the source chain.

What oracles do

A blockchain can only see data that lives on itself — it cannot check a stock price, a weather report, or even the state of a different blockchain on its own. An oracle is a service that fetches outside data, has multiple independent sources confirm it, and delivers it on-chain so smart contracts can use it. Bridges commonly rely on oracle-style networks to confirm that a lock or burn event genuinely happened on the source chain before minting anything on the destination chain.

Wrapped and multi-chain assets

A token you receive from a bridge is usually a "wrapped" version of the original — for example, wrapped Bitcoin (WBTC) on Ethereum is an ERC-20 token backed by real Bitcoin held in reserve, not Bitcoin itself moving onto Ethereum. Some assets skip a third-party bridge entirely: the issuer of the token mints and burns official supply directly on several chains, so each chain's version is a first-party original rather than a wrapped copy. Both approaches let the same asset exist on more than one network, but a wrapped asset carries the added risk of the bridge or reserve backing it, while an issuer-minted asset carries the risk of the issuer instead.

Worked example: USDT and USDC across networks

Tether (USDT) and Circle's USD Coin (USDC) are each issued directly by their company on several blockchains at once — as an ERC-20 token on Ethereum, a TRC-20 token on TRON, an SPL token on Solana, and more — rather than being wrapped copies of a single "original" version. Each network's balance is tracked entirely by that network's own ledger, so a USDT balance on TRON and a USDT balance on Ethereum are separate entries that don't automatically sync with each other. Moving USDT from Ethereum to TRON means sending it through an exchange or a bridge that redeems it on one chain and delivers the equivalent on the other — never a direct wallet-to-wallet transfer across networks, and never by sending an ERC-20 address's funds to a TRC-20 address, which would simply be lost.