Phi

Phi, often represented by the Greek letter φ, is an important mathematical constant approximately equal to 1.618. It is known as the golden ratio, which occurs when a line is divided into two parts in such a way that the ratio of the whole line to the longer part is the same as the ratio of the longer part to the shorter part. This ratio is aesthetically pleasing and can be found in nature, art, architecture, and design. It symbolizes balance and harmony, seen in everything from seashells to famous artworks like the Parthenon and the Mona Lisa.