The letter A began as a pictogram of an ox head in Egyptian hieroglyphs or the Proto-semitic alphabet.
Egyptian hieroglyph ox head
Proto-Semitic ox head
By 1600 BC, the Phoenician alphabet's letter had a linear form that served as the basis for some later forms. Its name must have corresponded closely to the Hebrew aleph. The name is also similar to the Arabic alif.
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 was 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.
The letter has two minuscule (lower-case) forms. The form used in most current handwriting consists of a circle and vertical stroke.
Most printed material uses a form consisting of a small loop with an arc over it (a). Both derive from the majuscule (capital) form.
In Greek handwriting, it was common to join the left leg and horizontal stroke into a single loop, as demonstrated by the Uncial version shown.
Many fonts then made the right leg vertical. In some of these, the serif that began the right leg stroke developed into an arc, resulting in the printed form, while in others it was dropped, resulting in the modern handwritten form.