- A full ontology-based application is a very complex system
 - Hard to implement, may be heavy to run…
 - … and not all applications may need it!
 - Three layers of OWL are defined: Lite, DL, and Full
						 
- increasing level of complexity and expressiveness
								
- “Full” is the whole thing
 - “DL (Description Logic)” restricts Full in some respects
 - “Lite” restricts DL even more
 
 
 - increasing level of complexity and expressiveness