An instrument rating allows you to fly with reduced visibility and in the clouds. This rating allows pilots to fly under Instrument Flight Rules (IFR) during weather conditions in which VFR (Visual Flight Rules) pilots are not permitted to operate.
To obtain this rating, you must have at least 35 hours of instrument instruction in a FAA Part 141 Approved flight school (non-approved schools require 40 hours). However, a realistic average is approximately 50 hours of flight training. You must also pass an FAA written examination and a flight fest with an FAA Designated Examiner. This rating would normally be sought following private pilot certification.