In this lecture, we delve into the realm of fact data modeling, focusing on the core concept of facts and addressing the challenges associated with handling duplicates. Our exploration underscores the pivotal role of facts in data engineering, shedding light on their significance. Practical insights into deduplication techniques are provided, and we discuss the ramifications of retention on fact data. Join us in this video to gain a comprehensive understanding of fact data modeling and its crucial implications in the field of data engineering.