Interlayer excitons are excitonic complexes that form in van der Waals heterostructures, where two-dimensional layers of different materials are stacked on top of each other with a small interlayer separation. These excitons are composed of an electron and a hole that are spatially separated between the two layers, resulting in unique optical and electronic properties. Studying interlayer excitons can provide insight into the fundamental physics of exciton formation and dynamics in low-dimensional materials. These excitons have been shown to have long lifetimes and large binding energies, making them promising candidates for applications in optoelectronics and quantum technologies. Research in this area focuses on understanding the formation, properties, and dynamics of interlayer excitons, as well as developing novel techniques to control and manipulate these excitonic complexes for future device applications.