The fundamentals of aviating haven’t changed terribly much since Orville and Wilbur first went skyward. A lot has evolved, but lift, drag, weather, aerodynamics and more really haven’t.
For that reason, a book that covers the timeless fundamentals while not being out-of-date is an invaluable asset on an bookshelf.

Bob Gardner’s “The Complete Private Pilot” (12th Edition) meets that description.
With chapters on Basic Aerodynamics, Aircraft Systems, Flight Instruments, Regulations, Procedures and Airport Questions, Weather, Weather Services, Aircraft Performance, En Route Flight, Navigation, Communication Procedures and Flight Planning, all aspiring and long-time pilots will be well served with this handy reference.
Most chapters conclude with review questions that will test your understanding.
While the title targets the Private Pilot, anyone seeking a Sport Pilot or Recreational Pilot certificate will also be well served.
The Complete Private Pilot (12th Edition) is available from Aviation Supplies & Academics for $24.95.