There is no generally agreed definition of what constitutes art

Official letters
A letter is a segmental symbol of a phonemic writing system. The inventory of all letters forms an alphabet. Letters broadly correspond to phonemes in the spoken form of the language, although there is rarely a consistent and exact correspondence between letters and phonemes.^[1]
The word letter, borrowed from Old French letre, entered Middle English around 1200 AD, eventually displacing the Old English term bōcstæf (bookstaff). Letter is descended from the Latin littera, which may have descended from the Greek "διφθέρα" (diphthera, writing tablet), via Etruscan.^[2]

Further information: Grapheme, Glyph, and Character (symbol)
A letter is a type of grapheme, which is a functional unit in a writing system: a letter (or group of letters) represents visually a phoneme (a unit of sound that can distinguish one word from another in a particular language). Letters are combined to form written words, just as phonemes are combined to form spoken words. A sequence of graphemes representing a phoneme is called a multigraph. A digraph is a case of polygraphs consisting of two graphemes.^[3] Examples of digraphs in English include ch, sh, and th. Some phonemes are represented by three letters, called a trigraph, such as sch in German.
The same letterform may be used in different alphabets but have different sounds. The letters ⟨H⟩, ⟨Η⟩ and ⟨Н⟩ look rather alike but are the Latin H, Greek eta and Cyrillic en respectively; conversely the letters ⟨S⟩, ⟨Σ⟩ (sigma) and ⟨С⟩ (Es (Cyrillic)) from these alphabets each represent (approximately) the same [s] sound. The basic Latin alphabet is used by hundreds of languages around the world,^[4] but there are many other alphabets.
Specific names are associated with letters, which may differ with language, dialect, and history. Z, for example, is usually called zed in all English-speaking countries except the US, where it is named zee. As elements of alphabets, letters have prescribed orders, although this too may vary by language. In Spanish, for instance, ⟨ñ⟩ is a separate letter, sorted separately from ⟨n⟩: this distinction is not usually recognised in English dictionaries. (In computer systems, each has its own unique code point, U+006E n N and U+00F1 ñ LATIN SMALL LETTER N WITH TILDE, respectively.)
Letters may also have a numerical or quantitative value. This applies to Roman numerals and the letters of other writing systems. In English, Arabic numerals are typically used instead of letters. Greek and Latin letters have a variety of modern uses in mathematics, science, and engineering.
People and objects are sometimes named after letters, for one of these reasons:

1. 
   The letter is an abbreviation, e.g. "G-man" as slang for a Federal Bureau of Investigation agent, arose as short for "Government Man"
   
2. 
   Alphabetical order used as a counting system, e.g. Plan A, Plan B, etc.; alpha ray, beta ray, gamma ray, etc.
   
3. 
   The shape of the letter, e.g. A-clamp, A-frame, D-ring, F-clamp, G-clamp, H-block, H engine, O-ring, R-clip, S or Z twist, U engine, U-bend, V engine, W engine, X engine, Z-drive, a river delta, omega block
   
4. 
   Other reasons, e.g. X-ray after "x the unknown" in algebra, because the discoverer did not know what they were
   

Engravings of decorated Latin letters, from the 18th century (note the lack of a J and a U)
Main articles: History of writing and History of the alphabet
Before there were alphabets there were pictographs: small pictures representing objects and concepts. Ancient Egyptian examples date to about 3000 BCE.^[5] Pictographs could communicate basic ideas, but were general and ambiguous if they were comprehensible at all. Grammatical tense, for example, could not be specified, and symbols do not necessarily carry meaning across cultures.
Memorization of tens of thousands of symbols is a daunting task; children from cultures that use logograms–word symbols–to represent words take years longer to learn to read and write than children learning an alphabet. The relative ease of memorizing 26 letters contributed to the spread of literacy throughout the world.^{[citation needed]}
The first consonantal alphabet found emerged around 1800 BCE to represent the language of the Phoenicians, Semitic workers in Egypt (see Middle Bronze Age alphabets), and was derived from the alphabetic principles of the Egyptian hieroglyphs. The Latin alphabet (used in Western and Central Europe and the former European colonies) derives from this Phoenician alphabet, which had 22 letters. Nineteen of the present letters of the Latin alphabet evolved from the early Phoenician forms; letter shapes and order of appearance correspond closely. The Greek alphabet, adapted around 800 BCE, added four letters to the Phoenician list. This Greek alphabet was the first to assign letters not only to consonant sounds, but also to vowels.^[6] The Roman Empire brought the development and refinement of the Latin alphabet, beginning around 500 BCE. The Romans added or dropped certain letters to accommodate Greek and Etruscan words; they also experimented with styles such as cursive when writing in ink. By about the fifth century CE, the beginnings of lowercase letterforms began to emerge in