Fibonacci is primarily celebrated for introducing the famous Fibonacci sequence, a series where each number is derived from adding the two preceding numbers. This sequence begins with 0 and 1, leading to numbers such as 1, 2, 3, 5, 8, and so on. Notably, as the sequence progresses, the ratio between consecutive numbers tends to approach the golden ratio, approximately valued at 1.618, which has captivated mathematicians and researchers for centuries.

This concept is detailed in Niall Ferguson's book, "The Ascent of Money: A Financial History of the World," where the connections between mathematics, finance, and natural patterns are explored. Ferguson highlights the historical significance of Fibonacci's work and its impact on various fields, illustrating how the sequence influences not only mathematics but also art, architecture, and economic theories.