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The letter A is the first letter in the Latin alphabet.

History

The letter A probably started as a pictogram of an ox head in Egyptian hieroglyphs or the Proto-semitic alphabet.

Egyptian hieroglyph
ox head

Proto-semitic
ox head

Phoenician aleph

Greek alpha
Greek alpha

Etruscan A

Roman A

By 1600 BC, the Phoenicians had given the letter a linear form that served as the basis for all later forms. Its name must have corresponded closely to the Hebrew aleph.

When the Ancient Greeks adopted the alphabet, they had no use for the glottal stop that the letter had denoted in Phoenician and other Semitic languages, so they used the sign for the vowel /a/, and changed its name to alpha. In the earliest Greek inscriptions, dating to the 8th century BC, the letter rests upon its side, but in the Greek alphabet of later times it generally resembles the modern capital letter, although many local varieties can be distinguished by the shortening of one leg, or by the angle at which the cross line is set.

The Etruscans brought the Greek alphabet to what is now Italy and left the letter unchanged. The Romans later adopted the Etruscan alphabet to write Latin, and the resulting letter was preserved in the modern Latin alphabet used to write many languages, including English.

Typography

The modern lowercase letter a derives from Greek handwriting, which evolved from a form similar to the current capital to a circular shape with a projection by the 4th century.

Blackletter A	Uncial A	Another Capital A
Modern Roman A	Modern Italic A	Modern Script A

Usage

In English, the letter A by itself usually denotes the lax open front unrounded vowel (IPA /æ/), as in pad, the open back unrounded vowel (IPA /ɑ/) or, in concert with a later e, the diphthong (though the actual pronunciation depends on the dialect), as in ace, due to effects of the Great vowel shift.

In most other languages that use the Latin alphabet, the letter a denotes either a open central unrounded vowel (IPA /a/), or an open back unrounded vowel (IPA /ɑ/).

In the International Phonetic Alphabet, variants of the letter A denote various vowels. In X-SAMPA, capital A denotes the open back unrounded vowel and lowercase a denotes the open front unrounded vowel.

Alternate representations

Alpha represents the letter A in the NATO phonetic alphabet.

In international Morse code the letter A is DitDah: · -

In Braille the letter A is represented as ⠁ (in Unicode), the dot pattern:

X.
..
..

Computing

In Unicode the capital A is codepoint U+0041 and the lowercase a is U+0061.

The ASCII code for capital A is 65 and for lowercase a is 97; or in binary 01000001 and 01100001, correspondingly.

The EBCDIC code for capital A is 193 and for lowercase a is 129.

The numeric character references in HTML and XML are "A" and "a" for upper and lower case respectively.

Meanings for A

In baseball, the Oakland Athletics are often simply referred to as the "A's".
In biochemistry, A is the symbol for alanine and adenosine.
In calendars, A is often an abbreviation for the months April and August.
In computing,
- <a> is the HTML element for an anchor tag.
- A sometimes represents the set of all alphabetic characters within string patterns.
In education, a grade of A typically represents the highest score that students can achieve. (sometimes coupled with a plus/minus sign - i.e., A+ or A-, or a number - e.g., A1)
In electronics,
- A is a standard size of battery.
- A refers to the Anode, or filament, component of a vacuum tube.
In film, A is an Italian film made in 1969; see A (film).
In financial securities, A is the stock symbol for Agilent Technologies.
In English, the word "a" is an indefinite article, see A, an
In Greek, a- is a prefix (alpha privativum) meaning "not" or "devoid of", used in many borrowed words in English, German and Romance languages.
In international licence plate codes, A stands for Austria.
In international paper sizes, A is a series of sizes with an aspect ratio of roughly 70% width to height, with A4 being an example popular size.
In logic,
- the letter A is used as a symbol for the universal affirmative proposition in the general form "all x is y". The letters I, E and O are used respectively for the particular affirmative "some x is y", the universal negative "no x is y", and the particular negative "some x is not y". The use of these letters is generally derived from the vowels of the two Latin verbs affirmo (or AIo), "I assert", and nego, "I deny". The use of the symbols dates from the 13th century, though some authorities trace their origin to the Greek logicians.
- In symbolic logic, the symbol ∀ (an inverted letter A) is the universal quantifier.
In mathematics,
- A is often used as a digit meaning ten in hexadecimal and other positional numeral systems with a radix of 11 or greater,
- blackboard bold $\mathbb {A}$ (𝔄 in Unicode) sometimes represents the algebraic numbers.
In medicine, A is one of the human blood types.
In the Metric system,
- A is the symbol for the ampere or amp, the SI base unit of electric current.
- a, atto, is the SI prefix meaning 10
- a is the symbol for the are, a unit of surface area equal to 100 square metres.
In music,
- A is a note.
- A, or "side A", refers to the top or first side of a vinyl record.
- A is an album by Jethro Tull; see A (album).
- A is a British rock band; see A (band).
In a deck of playing cards, the letter A is used to mark each of the Aces.
In political theory, a circumscribed "A" is an anarchist symbol.
As a timezone, A is the military designation for UTC+1, also known as CET or Central European Time.