Platelets are small, anucleate, discoid cell fragments essential for maintaining hemostasis by preventing blood loss and hemorrhages following vascular injury. Beyond their primary role in clot formation, platelets participate in wound healing, inflammation, and immune responses. Despite their lack of a nucleus, platelets are rich in bioactive molecules that enable them to detect vascular damage, adhere to injured vessels, and recruit other platelets and coagulation factors to halt bleeding. Given their critical functions, maintaining a proper balance of platelet production is crucial. At the center of platelet production is the megakaryocyte (MK), a specialized bone marrow (BM)-resident cell that undergoes a unique differentiation process to release platelets into the bloodstream. Understanding the biology of MKs and the intricate process of platelet formation is key to addressing both physiological and pathological conditions related to bleeding disorders and thrombosis. This chapter provides an in-depth exploration of MK development, platelet formation, and the regulatory mechanisms governing these processes.