DAML+OIL

Hello. Finally, I will continue para thesis. I have to do an example of
RDF technology, but i don't see or underestand the usage of OWL and DAML+OIL.
In which cases i have to use OWL and in which cases i must use pure RDF
without OWL onthology. 

I hope anybody can help me, 
thanks a lot,
Federico.

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FiberTel, el nombre de la banda ancha http://www.fibertel.com.ar