Many blockchains operate independently and have no way of communicating with other blockchains.
At a high level, communication between blockchains is important to avoid isolating ecosystems and creating excessive bottlenecks or suffocation.
Moreover, that opens the door for more research and leads to cross-innovations between systems.
The purpose of the existence of a bridge is to solve the problem of interoperability between blockchains.
See bridge as the ‘how’ the problem statement of interoperability - ‘why’ - can be executed.
The provided value is to enable the connection and transfer of messages; assets and data between different blockchains.
Thereby, Bridge is a system that receives assets from chain A and mirrors them to chain B.
The principal security idea is to ensure that the amount is well maintained between these two blockchains.
The ‘how’ bridge security is assured depends on different mechanisms.
- the token representation in chain B can be varied (wrapped; liquidity pool; canonical; native token)
- how funds are locked and managed (by a multisig;…)