Rafters – carry the load of the roof and are usually made of wood 2x4s
Wood Sheathing- also sometimes called decking, sheets of 1/2 thick plywood that are nailed to the rafters to provide a solid flat surface that the waterproofing materials can be attached to.
Felt Paper/Underlayment– the bottom layer of waterproofing. Felt paper impregnated with tar.
Roof Material– this is the covering, can be Shingles, Cap Sheet, or Clay Tiles.
Vents- Pitched roofs have vents that help control temperature inside the house and reduce energy cost
Flashing– metal strips or plastic covers that are used to make transitions and protrusions in the roof (bathroom vent pipes, skylights, chimneys) water tight.
Gutters/Scuppers and Downspouts– system used to channel rainwater collected from the roof, off it, and away from the house.
Licensing & Permitting
The California Contractor State License Board regulates contractors. Roofers are required to obtain a C-39 Roofing License from the state to work on roofs. I recommend to always hire a licensed roofer- roof repair and maintenance is highly specialized and not a job for a handyman.