Phi  (uppercase Φ, lowercase φ or ϕ) is the 21st letter of the Greek alphabet

You can rhyme it with fee or rhyme it with tie, it doesn't really matter.

Phi is also used as a symbol for the golden ratio and  has been  used in maths, science, art, music and architecture for millennia.

Phi occurs in nature and that's why its called the divine ratio. My video about the sacred geometry on this website explains this in simple detail.

All of the Meditation Pyramids and Connectors I design and build are based on the divine ratio.

That's why you can see the Phi symbol embossed on every corner