An(or) is a punctuation mark or, more pedantically, a tone mark[?] . Like the full stop (or period), it marks the end of a sentence that 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 !"

In type-setting or printing (and therefore when spelling text out orally), the exclamation mark is called a screamer or bang.

Frequent use of the exclamation mark, also called the mark of admiration, is common in writing by teenagers and in advertising.

Some brands cleverly, but confusingly, contain an exclamation mark, e.g. "Yahoo!".

The symbol is believed to originate from the Latin word io, an exclamation of joy. It was formed either as a digraph of the letters i and o, or as the letter i (for io) above a full stop.

In some languages, most notably Spanish, a sentence ending in an exclamation mark must also begin with an inverted exclamation mark, �.

See also: question mark, full stop

In computer programming, the exclamation mark corresponds to Unicode and ASCII character 33, or 0x0021.

Several computer languages use "!" for a variety of special 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, and in the BBC Basic[?] programming language it was called a pling.

In mathematics the symbol represents the factorial operation. For example, 3! (read 3 factorial) is 3 × 2 × 1 = 6.