This chapter summarizes and illustrates the histological background of the parathyroid glands as well as central pathologies affecting them. It goes into detail about different cell types found in the parathyroid glands and their morphological properties. Further it elaborates on entities most seen in parathyroid glands, such as parathyroid hyperplasia and adenoma, along with entities not to be missed, such as parathyroid carcinoma. Additionally, the role of immunohistochemistry in the work-up of parathyroid glands is explained. Finally, this chapter expands on the molecular background and genetic changes of these entities. It aims to provide the reader with a concise overview of the histopathology of parathyroid glands.