Definition:

An alphabeticsymbol such as A or a.

There are 26 letters in the modern English alphabet. Among the world’s languages, the number of letters ranges from 12 in the Hawaiian alphabet to 231 principal characters in the Ethiopian syllabary.

See Examples and Observations below. Also see:

• Alphabet
• Capital Letter
• Diacritic Mark
• Digraph
• Emoji
• From A to Z: Quick Facts About the Alphabet
• Grapheme
• Handwriting

• Logograph
• Logology
• Lower Case
• Orthography
• Parable: "The Invention of Letters"
• Silent Letter
• Spelling Rules
• Which Words in a Title Should Be Capitalized?
• Writing System

Etymology:
From the Latin, "shape or symbol used in writing"

Examples and Observations:

• "Because letters work at the phonemic level and are unencumbered by any extra baggage of sound, they achieve maximum efficiency. Our six letters of 'pencil' can easily be broken out and rearranged within countless other words--'lien,' 'Nile,' 'stipend,' 'clip,'--that sound nothing like 'pencil.' Letters are the original snap-on tools: They build on each other as necessary, so you actually need fewer items in your toolit. With 26, we capture reasonably well the approximately 500,000 words of English."
  (David Sacks, Letter Perfect: The Marvelous Story of Our Alphabet From A to Z. Broadway, 2004)
• From A to B
  "The symbol A indicated in Semitic a glottal consonant that did not exist in Greek. Its semitic name was 'aleph, the initial apostrophe here indicating the consonant in question; and, because the name means 'ox,' it has been thought to represent an ox's head, though interpreting many of the Semitic signs as pictorial characters presents as yet insuperable difficulties (Gelb 1963, pp. 140-41). By ignoring the initial Semitic consonant of the letter's name, the Greeks adopted this symbol as a vowel, which they called alpha. Beth was ultimately somewhat modified in form to B by the Greeks, who wrote it and other reversible letters facing in either direction; in the early days of writing they wrote from right to left, as the Semitic peoples usually did and as the Hebrew is still written. From the Greek modifications of the Semitic names of the first two letters, the word alphabet is ultimately derived."
  (Thomas Pyles and John Algeo, The Origins and Development of the English Language, 3rd ed., 1982)

• The Lighter Side of Letters
  "I'm good friends with 25 letters of the alphabet. I don't know Y."
  (Comedian Chris Turner, quoted by Mark Brown in "Edinburgh Fringe's 10 Funniest Jokes Revealed." The Guardian, August 20, 2012)