Question: Is there any clear definition of RPC and Web Service? A quick wikipedia search shows:

> 
> RPC: Remote procedure call (RPC) is an
>  Inter-process communication technology
>  that allows a computer program to
>  cause a subroutine or procedure to
>  execute in another address space
>  (commonly on another computer on a
>  shared network) without the programmer
>  explicitly coding the details for this
>  remote interaction. 
> 
> 
> Web Service: Web services are
>  typically application programming
>  interfaces (API) or web APIs that are
>  accessed via Hypertext Transfer
>  Protocol and executed on a remote
>  system hosting the requested services.
>  Web services tend to fall into one of
>  two camps: Big Web Services[1] and
>  RESTful Web Services.
> 
> 
> 

I am not quite clear what the real difference between the two things. It seems that one thing could belong to RPC and is kind of web service at the same time.

Is Web Service a higher level representation of RPC?

Answer: 
> 
> Is Web Service a higher level
>  representation of RPC?
> 
> 
> 

Yes, it is. A web service is a specific implementation of RPC. At its lowest level, Web Service connects to the Socket, using the HTTP protocol, to negotiate sending a payload that is executed in a remote space (remote space can be the same computer). All these remote call abstractions, at its core, are RPCs.
I see this question. The question has been asked long time ago, but I think anyone's answer in this community, giving more information and clarity on this topic, will be helpful for the future questioners. So, I would like to add my enhancement pointing out key differences and I hope, it will be helpful for future readers.

```
------------------------------------------------------------------------------
| Category             |    RPC              |    Web Services
------------------------------------------------------------------------------
|Operation's Location  | On top of TCP       | on top of HTTP Protocol
------------------------------------------------------------------------------
|Data format           | Binary              | Text, XML, JSON, ect.
------------------------------------------------------------------------------
|Speed                 | Slow (Marshalling)  | Fast
------------------------------------------------------------------------------

```

I have not mentioned descriptions of RPC and Web Services, because you see them in others' answer clearly.