1.  Phī is the twenty-first letter in the Greek alphabet.

2.  Phī is a labial aspirate consonant. Its phoneme is pronounced by the near closing of the lips and accompanied breath. Its phoneme sounds like the "ph" as in "phone" or the "f" as in "fat."

3.  Phī's lower case letter is written like its capital letter except the capital letter's stem sits on the base line whereas the body of the lower case letter rests on the base line.

4.  Phī's lower case letters may be easily confused when written. Special care needs to be exercised. Form upsīlon with a rounded bottom with the right upward stroke turned outward.

5.  Phī is always transliterated into English with two consonants, "Ph" or "ph."