 The studies of the composition and structure of comet 67P/Churyumov–Gerasimenko—a short-period comet of Jupiter’s family—which was an object of the recent Rosetta–Philae space mission, yielded results unique in many respects, since it was the first time that a comet was investigated in situ for a long stretch of time under varying conditions of insolation and activity. Due to the landing of the Philae probe, the data on the composition of mineral and organic fractions sampled directly from the cometary nucleus were obtained. Measurements of the coma composition performed with the instruments onboard the Rosetta spacecraft in the early period of observations allowed the data on the composition of its extremally volatile components (N2 and Ar) to be acquired for the first time, while the analysis of the coma composition performed in the postperihelion period provided an adequate insight into the composition of the ice fraction of the cometary nucleus. In the review, along with consolidating the experimental data, we discuss their implications arising in the context of cosmogony and cosmochemistry.