The technique of comprehensive two-dimensional gas chromatography (GCxGC) is reviewed. A description of technical aspects of the method illustrates how the GCxGC result is achieved through the use of dual-coupled columns and the modulation of capillary chromatographic peaks. This review presents an expanded section dealing with the relationship between the modulation phase and frequency and the resulting peak pulse profiles. Experimental results that support the appreciation and understanding of the effects that pulsing has on a chromatographic peak are provided. The main goals of GCxGC analysis are discussed with respect to analytical sensitivity and peak capacity arising from zone compression effects and fast analysis on the second column. A typical application of GCxGC is presented, along with a consideration of implementation of the GCxGC method.