Petrology is one of the fundamental sciences of geology. It mainly includes studies of the chemical composition, mineral composition, structure, form, classification, formation conditions, distribution, occurrence, combinations, mineralization relationships, evolution and changes of rocks. Petrology is the foundation of regional geological surveys, mineral exploration, hydrogeology, engineering geology, environmental geology, geochemistry, geophysics, agricultural geology, disaster geology and tourism geology. Based on the research focus, it can be divided into igneous petrology, sedimentary petrology, metamorphic petrology, rock chemistry, rock groups, experimental petrology, technical petrology, regional petrology, landscape petrology and ornamental petrology. Rocks and landscapes with aesthetic value are usually important for geological landscape tourism.