Anything that can be registered with and made available via the 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). The Ocean network supports 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). [OEP-11](https://github.com/oceanprotocol/OEPs/tree/master/11) is a technical specification of how SEAs mediate access control.
