In this review, the essential aspects of gas chromatography are discussed. The article begins with a very brief discussion of basic chromatographic theory, followed by an in-depth treatment of the instrumentation involved. This discussion starts a discussion of chromatographic columns, the distinctions among which are used to classify the different modes of gas chromatography. Following this is an in-depth discussion of instrumentation, the treatment of which follows the classification by column types; This discussion includes the operational principles and applications of injectors, detectors and data handling systems. In conclusion, a listing of suggested further reading is provided.