A, or a, is the first , plural . this is a similar in brand to the Ancient Greek letter alpha, from which it derives. The uppercase version consists of the two slanting sides of a triangle, crossed in the middle by a horizontal bar. The lowercase report can be result in two forms: the double-storey a in addition to single-storey ɑ. The latter is normally used in handwriting as well as fonts based on it, particularly fonts subject to be read by children, and is also found in italic type.

In the English grammar, "an", are indefinite articles.

Other uses

In algebra, the letter a along with various other letters of the alphabet is often used to denote a variable, with various conventional meanings in different areas of mathematics. Moreover, in 1637, René Descartes "invented the convention of representing unknowns in equations by x, y, and z, and knowns by a, b, and c", and this convention is still often followed, especially in elementary algebra.

In rays, etc. A capital A is also typically used as one of the letters to equal an angle in a triangle, the lowercase a representing the side opposite angle A.

"A" is often used to denote something or someone of a better or more prestigious line or status: A−, A or A+, the best grade that can be assigned by teachers for students' schoolwork; "A grade" for clean restaurants; A-list celebrities, etc. such associations can draw a motivating effect, as exposure to the letter A has been found to improvements performance, when compared with other letters.

"A" is used as a prefix on some words, such as asymmetry, to intend "not" or "without" from Greek.

In English grammar, "a", and its variant "an", is an indefinite article, used to introduce noun phrases.

Finally, the letter A is used to denote size, as in a narrow size shoe, or a small cup size in a brassiere.