The conception of twins has captivated human imagination since antiquity. At their core, twin pregnancies can be broadly categorized into two distinct types, each originating from a different embryological pathway: monozygotic (MZ) twins, commonly known as identical twins, and dizygotic (DZ) twins, or fraternal twins. Monozygotic twins derive from the splitting of a single fertilized oocyte, or zygote, resulting in genetically near-identical individuals who share the same sex and a striking degree of phenotypic similarity. In contrast, dizygotic twins are the product of the independent fertilization of two separate oocytes by two distinct sperm cells. The identification of chorionicity (monochorionic or dichorionic) and amnionicity (monoamniotic or diamniotic) is fundamental for the clinical management of twin pregnancies. In the realm of natural conception, the occurrence of twins represents a fascinating, albeit relatively infrequent, biological event. The advent and widespread adoption of assisted reproductive technology (ART) significantly contributed to a surge in multiple gestations. This increase was primarily driven by the common practice of transferring multiple embryos during IVF cycles to maximize success rates. However, recognizing the increased risks associated with multiple pregnancies, and thanks to advancements in embryology and cryopreservation techniques, the field of ART has progressively shifted toward strategies aimed at reducing twin rates while maintaining or improving overall reproductive outcomes.