Lowercase ? (in two story form) is used in the International Phonetic Alphabet to identify the near-open central vowel. This is not to be confused with the turned alpha or turned script a, ?, which is used in the IPA for the open back rounded vowel.
It was used in the 18th century by Edward Lhuyd and William Pryce as phonetic character for the Cornish language. In their books, both ? and ? have been used.  It was used in the 19th century by Charles Sanders Peirce as a logical symbol for 'un-American' ("unamerican").
The symbol ? has the same shape as a capital turned A, sans-serif. It is used to represent universal quantification in predicate logic. When it appears in a formula together with a predicate variable, they are referred to as a universal quantifier. In traffic engineering it is used to represent flow, the number of units (vehicles) passing a point in a unit of time.
|Unicode name||LATIN CAPITAL LETTER TURNED A||LATIN SMALL LETTER TURNED A||FOR ALL|
|UTF-8||226 177 175||E2 B1 AF||201 144||C9 90||226 136 128||E2 88 80|
|Numeric character reference||Ɐ||Ɐ||ɐ||ɐ||∀||∀|
|Named character reference||∀|