Summary of week four for the course Knowledge Engineering with Semantic Web Technologies 2015 by Harald Sack at OpenHPI.
RDFS Semantics: we need this because there was no formal description of the semantics and then the same querys gave back different results. So you add semantics. Every triple encoded in RDF is a statement and also a RDF-graph is also a statement.
OWL: based on a description logic it consists of classes, properties and individuals (instances of classes)
OWL2 has different flavors with three different dialects (EL, RL, QL), DL (based on description logic and Full (DL is decidable, Full is not). There are different ways to create ontologies. The most important (and shortest) are Manchester Syntax and Turtle.
Classes, properties and individuals in OWL are comparable with the ones in RDFS.
OWL contains NamedIndividuals, which can be introduced directly.
An editor for Ontologies is protege, which can be used as web or desktop application, there are also short courses at their homepage.
Deeper knowledge about OWL in the extra lectures.