The golden ratio, or the Greek letter Phi, is a mathematical ratio rounded off to 1.618. It frequently appears in nature in objects we find beautiful, such as flowers and shells. Leonardo da Vinci used the golden ratio when painting the Mona Lisa and The Last Supper. It's natural we would want to incorporate the golden ration in web design.
While designers learn about the golden ratio in school, it's possible for someone who has never heard of the ratio to design an aesthetically pleasing website. Unconsciously, we replicate natural proportions if we've seen enough websites.
UX designers use the golden ratio to create golden rectangles when creating wireframes. To create a sidebar, they take the total width of the layout and divide it by 1.618 to get the content area and what is left is the sidebar. A simpler way is to apply the rule of thirds. Divide the width of your layout into three equal parts. Do the same thing with the height. Place the most important elements of your website in the four places where the lines intersect.
Some web designers will disagree with the idea that humans find the golden ratio aesthetically pleasing. There's no scientific data to support the theory. In fact, test subjects in repeated experiments were asked to pick their favorite rectangle out of a random group of rectangles, one of which was a golden rectangle. People chose random rectangles. If the golden triangle was so pleasing to the eye, test subjects should have favored it, but they didn't.
Using golden ratio is not a foolproof way to create a great website; many other factors go into a successful design. However, it will balance and create harmony and balance and visitors will unconsciously feel comfortable. It's a tool website designers can use, but it isn't a rule. For more information click here https://www.reddit.com/r/web_design/comments/c6w0jw/is_the_golden_ratio_a_pure_cognitive_bias_in_term/.