Letters of the alphabet

A letter is a grapheme (written character) in an alphabetic system of writing. It is a visual representation of the smallest unit of spoken sound. Letters broadly correspond to phonemes in the spoken form of the language, although there is rarely a consistent, exact correspondence between letters and phonemes.

Written signs in other writing systems are called syllabograms (which denote a syllable) or logograms (which indicate a word or phrase).

The contemporary English-language alphabet, known as Roman style, consists of twenty-six letters. Each letter corresponds to one or more sounds, and the letters are combined in the order of sounds to make words. A letter is classed as either a consonant or a vowel, depending on how its sound is produced (vowels are a, e, i, o, u, and sometimes y and w).

The basic Roman alphabet is used by about one hundred languages, with slight variations. Some versions contain as few as twenty-one characters, some as many as thirty. Letters have specific names associated with them, 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 after n. In English, n and ñ are classified alike.

As symbols that indicate segmental speech, letters are associated with phonetics. In a purely phonemic alphabet, a single phoneme is denoted by a single letter, although in history and in practice letters often indicate more than one phoneme. There are more sounds, or phonemes, in English–about 44–than there are letters of the alphabet. A letter may therefore be associated with more than one phoneme, with the phoneme determined by the surrounding letters or etymology of the word. Regional accents have a significant effect; the letter a can range from five to twelve sounds depending on the origin of the speaker. As an example of positional effects, the letter c is pronounced [k] before a, o, u, or consonants (e.g. critical), but is pronounced [s] before e, i, or y (e.g. democracy). Conversely, the same phoneme may be shared by more than one letter, as shown by the c and s in fence and tense. A pair of letters designating a single phoneme is called a digraph. Examples of digraphs in English include ch, sh, and th. A phoneme can also be represented by three letters, called a trigraph. An example is the combination sch in German.

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