Platelet activation is the process by which platelets, small blood cells involved in clotting, become activated in response to signals from damaged blood vessels or other stimuli. When platelets are activated, they undergo changes in shape, release granules containing clot-promoting substances, and form aggregates to help stop bleeding. Platelet activation plays a critical role in hemostasis, the process of preventing and stopping bleeding, as well as in the formation of blood clots in response to injury or disease. Research in platelet activation aims to understand the mechanisms that regulate this process and develop new strategies for modulating platelet function in various clinical conditions, such as thrombosis, atherosclerosis, and bleeding disorders.