> For the complete documentation index, see [llms.txt](https://qualitax.gitbook.io/interop/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://qualitax.gitbook.io/interop/bridging-approaches/relayers.md).

# Relayers

Entity that relays transactions and messages between different blockchains to enable crosschain communication.

The main functions performed by relayers are:

* Watching activity on multiple chains and detecting relevant transactions or state changes that need to be relayed across chains.
* Validating that the transactions/messages follow the expected formatting and protocols of the source and destination chains. This ensures security and smooth relaying.
* Relaying or reproducing the transactions on the destination chain in a manner recognizable and valid on that chain. May involve reformatting transactions or creating proxy contracts.
* Providing proof of the original transaction from the source chain to the destination chain so it can be verified. For example, passing cryptographic proofs.
* Maintaining operational reliability to relay transactions in a timely and predictable manner between chains.
* In some cases, providing various incentives to decentralized relayers for reliable message relaying services.

The relationship between relayers and bridges in the context of blockchain interoperability is as follows:

* Bridges are the overall infrastructure and architecture that enables interoperability between two or more chains.
* Relayers are components within a bridge that perform the actual relaying of transactions and messages between the chains.
* Bridges establish the network connections, protocols, mechanisms like hash-locking, data formats etc. to facilitate crosschain communication.
* Relayers operate on this bridge infrastructure to monitor chains, detect relevant transactions, validate formatting, and relay information between chains.
* A single bridge may employ one or more relayers operating in parallel for load balancing, redundancy etc.
* Relayers provide a pluggable component within bridges for upgrading relaying algorithms, incentives, APIs etc.

So in summary:

* Bridges provide the overall infrastructure.
* Relayers are modular components within bridges that execute transaction and message relaying.
* Bridges establish the facilities for interoperability.
* Relayers do the actual information relaying on this infrastructure.

Therefore, relayers provide an operational component within the overall bridge architecture for interoperability.