Factory service manuals (FSM) are the manuals provided by manufacturers which cover the servicing, maintenance and repair of their products. They were not originally offered to the public as they were developed for the dealerships so that their mechanics were able to fix their own products.
Many after-market manuals are available, with most of them referencing the FSM for topics such as torque specifications, dimensions and part numbers.
For vehicles, the following content are usually covered: body, frame & mounting, engine, suspension, driveline, brake systems, transmission/transaxle, clutch, chains, exhaust, fuel, steering, shocks, climate control, instrumentation & Warnings Systems, battery & charging systems, audio, lighting, electrical distribution, and wiring.