The article discusses the composition of zircon and its role in igneous and metamorphic petrogenesis. Zircon is a common mineral in igneous and metamorphic rocks, serving as a host for significant fractions of U, Th, Hf, and REE. These elements are important for geochemical studies, particularly in U-Th-Pb geochronology and understanding the temporal evolution of the crust and lithospheric mantle. Recent studies have focused on the composition of zircon, particularly trace elements, to better constrain in situ microprobe-acquired isotopic ages. Advanced analytical techniques, such as electron-beam compositional imaging and isotope-ratio measurement, have revealed that single zircon crystals can contain records of multiple geologic events, which may be separated by millions or billions of years. However, calculated zircon isotopic ages often do not match those determined from other minerals or whole-rock analysis, prompting investigations into zircon composition to interpret these ages. Zircon's ability to influence or record petrogenetic processes in igneous and metamorphic systems is also highlighted. The article reviews analytical techniques used for zircon compositional analysis, including INAA, ID-TIMS, and ICP-MS. These techniques have revealed that zircon compositions can vary significantly, with some analyses showing higher REE, Th, U, and other elements compared to in situ microprobe techniques. The use of zircon trace-element composition as a provenance indicator of detrital or xenocrystic zircon is also discussed. The article further explores the major-element composition of igneous zircon, noting its zirconium orthosilicate structure and variations in Hf and Zr abundances. Trace-element composition of igneous zircon is analyzed, with a focus on substitution mechanisms and the influence of REE on zircon structure. The article also discusses the REE patterns of zircon, noting variations in HREE and LREE abundances and the presence of Ce and Eu anomalies. These anomalies are influenced by factors such as oxidation state and magma composition. The article concludes with a discussion of the significance of zircon in understanding the petrogenesis of igneous and metamorphic rocks, including its role in crustal evolution and the differentiation of zircon in different rock types.The article discusses the composition of zircon and its role in igneous and metamorphic petrogenesis. Zircon is a common mineral in igneous and metamorphic rocks, serving as a host for significant fractions of U, Th, Hf, and REE. These elements are important for geochemical studies, particularly in U-Th-Pb geochronology and understanding the temporal evolution of the crust and lithospheric mantle. Recent studies have focused on the composition of zircon, particularly trace elements, to better constrain in situ microprobe-acquired isotopic ages. Advanced analytical techniques, such as electron-beam compositional imaging and isotope-ratio measurement, have revealed that single zircon crystals can contain records of multiple geologic events, which may be separated by millions or billions of years. However, calculated zircon isotopic ages often do not match those determined from other minerals or whole-rock analysis, prompting investigations into zircon composition to interpret these ages. Zircon's ability to influence or record petrogenetic processes in igneous and metamorphic systems is also highlighted. The article reviews analytical techniques used for zircon compositional analysis, including INAA, ID-TIMS, and ICP-MS. These techniques have revealed that zircon compositions can vary significantly, with some analyses showing higher REE, Th, U, and other elements compared to in situ microprobe techniques. The use of zircon trace-element composition as a provenance indicator of detrital or xenocrystic zircon is also discussed. The article further explores the major-element composition of igneous zircon, noting its zirconium orthosilicate structure and variations in Hf and Zr abundances. Trace-element composition of igneous zircon is analyzed, with a focus on substitution mechanisms and the influence of REE on zircon structure. The article also discusses the REE patterns of zircon, noting variations in HREE and LREE abundances and the presence of Ce and Eu anomalies. These anomalies are influenced by factors such as oxidation state and magma composition. The article concludes with a discussion of the significance of zircon in understanding the petrogenesis of igneous and metamorphic rocks, including its role in crustal evolution and the differentiation of zircon in different rock types.