What's the relationship between OWL, RDFs, RDFa, Dublin Core and FOAF?

Question

Semantic web can be described as Layer Structure. we have URI in the button layer which is the unique identifier for data. and then we hay syntax like : xml, ns and xml xmls next it is the way how can we interpret semantic data : RDF and above RDF, we have RDFs, and OWL is independent from RDFs? but OWL, Dublin Core and FOAF is kind of RDFa? what's the structure between those ?

Answer 1

Dublin Core and FOAF are schemas, ie vocabularies you can use to mark up your data.

OWL (and RDFS) are languages for writing new schemas / vocabularies / ontologies. OWL and RDFS schemas are written using RDF.

RDFa is a syntax for writing RDF (other examples are RDF/XML and Turtle).

Yes, this is all quite confusing!