The fundamental theory and technology of gas chromatography (GC) are reviewed with an eye toward assisting new users to become familiar with GC and to begin using to solve analytical problems. Theory and data analysis, including gas flows, band broadening and retention on columns is discussed. Instrumentation is reviewed, including inlets, column, detectors and data systems. Special topics, including multidimensional gas chromatography, fast and micro‐GC are introduced. Although new inlets such as programmed temperature vaporization are available and more versatile, split and splitless injection remain the mainstays of sample introduction. Column technology has evolved significantly in the last decade with myriad specialty stationary phases now available in capillary columns. Flame ionization remains the most common detector, although mass spectrometry has become less expensive and complicated and more widely used. There have been tremendous advances in multidimensional gas chromatography. Numerous references to literature and extensive reference sources are included. In 2010, gas chromatography is one of the most versatile and widely used instrumental techniques.