What is blood coagulation? Enumerate the various steps involved in blood coagulation. (UPSC 2020, 15 Marks, )

रक्त का थक्का जमना क्या है? रक्त के थक्का जमने की विभिन्न प्रक्रियाओं को सूचीबद्ध करें। (What is blood coagulation? Enumerate the various steps involved in blood coagulation.)