Basically, I know that RDF, RDFS, and OWL are used to define the ontologies in order to address the semantics problem in world wide web.
However, these terms make me a bit confused when studying them. This is my conclusion regarding their relationship after reading this article. Please correct me if I get wrong
Resource Description Framework (RDF). As its self-explained name, it is just a framework that describes the resources in term of a graph.
RDF Schema (RDFS). It is a set of possible relationships that could be used in RDF.
Web Ontology Language (OWL). It is even an extended set of possible relationships for an RDF graph.
Furthermore, what is the status of semantic web technology? Is it still in the research phase, or is it already adopted in production?
This question might be out of scope for Stackoverflow, but basically:
There are definitely people using Semantic Web Technologies (aka Linked Data) in production, mostly to integrate various data sources. But it definitely hasn't taken off the way HTML or XML have.
Where it's trickled somewhat into the mainstream is with Facebook's Open Graph (which is technically not quite RDF unfortunately), Google's Structured Data and schema.org.