Any EVM-compatible network where all[^1] the Ocean Protocol smart contracts ([keeper contracts](https://github.com/oceanprotocol/keeper-contracts)) are deployed. There can be many Ocean networks. Examples include the [testnets](/concepts/testnets/) and [the Ocean Production Network](/concepts/production-network/).
Note: Some old documentation refers to "the Ocean Network" or "the Ocean Protocol Network." You will have to guess which network was meant, based on the context.
Anything that can be registered with and made available via an Ocean Network. Examples include data sets, trained model parameters, pipelines, and data-cleaning services.
A service where publishers can list what assets they have, and consumers can see what's available then buy it (or get it for free). Every marketplace has a database where they store metadata about the assets they know about (but not the assets themselves). An Ocean network can support many marketplaces.
A person or a software service that checks some steps in transactions. For example, a verifier might check to see if a cryptographic signature is valid and then get rewarded for doing so.
A contract-like agreement between a publisher, a consumer, and a verifier, specifying what assets are to be delivered (from publisher to consumer), the conditions that must be met, and the rewards for fulfilling the conditions.
We published an [Ocean Protocol blog post that explains SEAs in more detail](https://blog.oceanprotocol.com/exploring-the-sea-service-execution-agreements-65f7523d85e2).
