Once you have your private pilot license, you may find that you're limited on certain days by the weather. Obtaining your instrument rating makes your pilot's license much more versatile. It allows you to fly with lower cloud ceilings and decreased visibility and will make your pilot's license useable much more of the time. The instrument rating enables a pilot to fly under Instrument Flight Rules (IFR). It requires additional training and instruction beyond what is required for a private pilot or commercial pilot certificate, including rules and procedures specific to instrument flying, additional instruction in meteorology and more intensive training in flight solely by reference to instruments.
For most private pilots, the most significant value of flying IFR is the ability to fly in instrument meteorological conditions. Additionally, all flights operating in Class A airspace, defined as the airspace from 18,000 feet MSL up to 60,000 feet, must be conducted under IFR.