The Golden Ratio, also known as the divine proportion, golden mean or golden section, is basically a number represented by Phi (either uppercase Φ or lowercase φ). This number is approximately equal to 1.618 and is present in many things (more than we expect), such as in atoms, music, arts, nature and so on. As you see, it’s just like Pi, but with different values and mysteries. As an example, we can take the Parthenon, in Athens, Greece.
Some people, especially the Greeks, believe that Pythagoras and his followers discovered the Divine Proportion, because their symbol was a regular pentagram with a regular pentagon inscribed within it, which is also a representation of the golden section.
There are many unanswared questions about the Golden Proportion, questions that we might never discover the answers. But, we can be sure about one thing: the nature is perfect.