The fibonacci sequence is found in nature, created by the universe, discovered by math, and is the most pleasing visual pattern to humans when converted into a swirl. We use this principle in web design by establishing a grid for many of our site designs. While it's fun to break out of traditional grid systems occasionally, even non-traditional sites get the fibonacci treatment, or golden ratio.
Web design grids follow the mathematical and aesthetically pleasing fibonacci sequence. The most important part of designing of website is to draw the attention to the critical aspects of the page- usually contact information and navigation first. Images can draw you in and feel welcoming, and the natural flow of the website leads you to the critical elements of the site.
The fibonacci sequence can be flipped or reversed, and good site design should still draw you into the most important aspects of the website.
The next time you're looking at a seashell, center of a sunflower, or your thumbprint (made ya look!), think of the fibonacci sequence, and remember good site design follows the same principles.