Higher Secondary Examination (12th board examination) is a centralized examination for class 12 students in India, Bangladesh, Nepal and Pakistan. All the State School Education Boards, CBSE, CISCE and NIOS conduct exams during the period of March–April every year for students in their affiliated private and public schools. The number of subjects, types of examination (theoretical, practical or both) and grading methods differ among the boards and states. Clearing HSC is mandatory for pursuing higher education or undergraduate courses in India. In India, 10th board examination is referred by SSC (Secondary School Certificate) while 12th board examination is referred by SSSC (Senior Secondary School Certificate).
Higher Secondary Examination is called by different names across India. CBSE, CICSE, and state boards of education conduct 12th class examination on their level for class 12 students in their schools. The examination time frame may be the same or different for the boards. Each board issues its separate time table for higher secondary examinations. (Sources WikiPedia)