As vitrectomy surgery allows access to the vitreous, retina, and choroid, it is used in many clinical pathologies. There is a wide range of indications for vitrectomy surgery including intraocular bleeding, epiretinal membrane (ERM) involving the posterior pole, macular hole, vitreomacular traction, tractional and rhegmatogenous retinal detachment, diabetes-related subhyaloid hemorrhage, membranes, subretinal hemorrhage, trauma, foreign body, endophthalmitis, lens fragment removal after complicated lens surgery, and tumor biopsy or excision. Different techniques specific to each pathology may be required during surgery. Perhaps the only contraindication for vitrectomy surgery is malignant tumors that carry the risk of intraocular or systemic spread. Even in such cases, evaluations can be made on a case-by-case basis, and surgery can be performed according to the recommendations of ocular oncologists. This section explains the basic principles of pars plana vitrectomy surgery. Indication-specific surgical methods are described in more detail in the following chapters.