A (disambiguation)

A is the first letter of the alphabet. It may also refer to:

In English, it is one of the two indefinite articles, the other being an.
 In measurement, A is a symbol for area.
 In medicine, A is one of the human blood types.
 In music, A is a note.
 In the International System of Units, A is the symbol for the ampere (which is also shortened to amp).
 In school, an A+ is the highest grade you can get, with an A being the grade below.
 In transport, A is the international license plate code for Austria.
In the New York Stock Exchange, A is the symbol for Agilent Technologies.
In the Cyrillic Script, А is the first letter.
Ampere, a unit of electric current