Science Fair Project Encyclopedia
An exclamation mark (also exclamation point, and (rarely) mark of admiration) is a punctuation mark. Like the full stop (or period), it marks the end of a sentence. A sentence ending in an exclamation mark is either an actual exclamation ("Wow!"), a command ("Stop!"), or is intended to be astonishing in some way ("They were the footprints of a gigantic hound!").
For use of spaces after an exclamation mark, see the discussion for the full stop.
Frequent use of the exclamation mark is common in writing in advertising. Some brands cleverly, but confusingly, contain an exclamation mark (examples include the search engine Yahoo! and the game show Jeopardy!) Some comic books, especially superhero comics of the mid-20th century, routinely use the exclamation mark instead of the period. Overuse of the exclamation mark is generally considered poor writing, since it distracts the reader and reduces the mark's meaning. Some authors however, most notably the American Tom Wolfe, are known for unashamedly liberal use of the exclamation mark.
The English town of Westward Ho!, named after the novel by Charles Kingsley, bears the only place name in the United Kingdom that officially contains an exclamation mark. There is a town in Quebec called Saint-Louis-du-Ha! Ha!, which officially contains two exclamation marks in its name. The titles of several musical comedies such as Oklahoma! and Oh! Calcutta! also contain exclamation marks.
- ¿Estás loco? ¡La mataste!
In Khoi, Bushmen, and the International Phonetic Alphabet, the exclamation mark is used as a letter to indicate the retroflex "click" sound represented as q in Zulu orthography. In Unicode this letter is properly coded as U+01C3 (ǃ) and distinguished from the common punctuation symbol U+0021 (!) to allow software to deal properly with word breaks.
There is a punctuation mark intended to combine the functions of a question mark and an exclamation mark in English called interrobang, which resembles those marks superimposed over one another ("‽") but the sequence of "?!" is used more often.
Exclamation marks are used to emphasize a warning .
On warning signs an exclamation mark is often used to draw attention to a warning of danger, hazards and the unexpected. These signs are common in hazardous environments or on potentially dangerous equipment. A common type of this warning is a yellow triangle with a black exclamation mark, but a white triangle with a red border is common on European road warning signs.
In fan fiction, "!" is used to signify a defining quality in a character, as in romantic!Draco from Harry Potter fandom. Almost always the character in question is a canon character, and most often the quality is one that is unusual, or non-canon. Occasionally, the "!" notation will describe a physical appearance thought to trigger certain reactions, as in shirtless!Vaughn from Alias. The origin of this usage is unknown.
In mathematics the symbol represents the factorial operation. n! means "the product of the integers from 1 to n". For example, 4! (read four factorial) is 4 × 3 × 2 × 1 = 24. (0! is defined as 1, which is a neutral element in multiplication, not multiplied by anything.)
Several computer languages use "!" for a various meanings, most importantly, logical negation, e.g. A ! = B means "A is not equal to B". In this context, the exclamation is named the bang character; other programmers call it a shriek. Invented in the US, it is claimed that the first term is from Unix and the second from Stanford or MIT. In the BBC BASIC programming language it is called a pling and is used to reference a 32-bit word (see also: Shebang).
In the Geek Code, "!" is used before a letter to denote that the geek refuses to participate in the topic at hand.
When computer programs display messages that alert the user, an exclamation mark may be shown alongside it to indicate that the message is important and should be read. This often happens when an error is made, or when the computer may do an unsafe operation, such as deleting a file.
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