Summary
Fibonacci Sequence is a series of numbers with the pattern of each number being the sum of the previous two. Starting at zero the sequence will be 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144…
The sequence is relevance to design because it is close to objects in nature. For example, tree branches, flower artichokes, and the arrangements of leaves on a stem.
The sequence is usually used together with the golden ratio (1.618), the visually pleasant proportion ratio of an object. A lot of classical artworks are designed based on the Fibonacci pattern.
Resource Example
The naturally harmonious design of the human form.

Other Example
Fibonacci sequence in nature.

Life Example
Fibonacci sequence in the yard.

Strategy: Fibonacci Sequence

What is the Golden Ratio?
Closely related to the Fibonacci Sequence (which you may remember from either your school mathematics lessons or Dan Brown’s novel The Da Vinci Code), the Golden Ratio describes the perfectly symmetrical relationship between two proportions.
Approximately equal to a 1:1.61 ratio, the Golden Ratio can be illustrated using a Golden Rectangle: a large rectangle consisting of a square (with sides equal in length to the shortest length of the rectangle) and a smaller rectangle.
If you remove this square from the rectangle, you’ll be left with another, smaller Golden Rectangle. This could continue infinitely, like Fibonacci numbers – which work in reverse. (Adding a square equal to the length of the longest side of the rectangle gets you increasingly closer to a Golden Rectangle and the Golden Ratio.)
Ancient Greek architecture used the Golden Ratio to determine pleasing dimensional relationships between the width of a building and its height, the size of the portico and even the position of the columns supporting the structure.
The final result is a building that feels entirely in proportion. The neo-classical architecure movement reused these principles too.
Source: http://www.creativebloq.com/design/designers-guide-golden-ratio-12121546