What is a simple roof definition?

Roof definition refers to all the elements covering the building: 
- the roofing materials (clay tiles, metal sheets, shingles, bitumen corrugated sheets and tiles…) 
- the wooden or metal structure that supports them, made of the intermediate purlins, rafters and battens. 

View of an insulated roof:  
1 Insulation  
2 Waterproofing Underlay
3 Vapour barrier  
4 Ventilation gap  
5 Roofing  
6 Counter batten  
7 Rafter 

Drawing of the roofing structure