The central or most important part of something.

किसी चीज़ का केंद्रीय या सबसे महत्वपूर्ण भाग।

English Usage: "The core of the debate was about education reform."

Hindi Usage: "चर्चा का केंद्रीय विषय शिक्षा सुधार था।"

A foundational or essential course that is required in a curriculum.