An interrobang is a rarely used symbol in English typography that combines the forms of the exclamation point and the question mark. It looks essentially like an exclamation point with a question mark growing out from about the midpoint of the straight line, with both marks sharing the same point and the hook of the upper curve on the question mark just over-reaching the top of the exclamation point. The name interrobang is derived from the Latin interrogatio, which is a type of interrogative question, and the slang term bang, used by printers and typographers to refer to the exclamation point. Other names that were initially proposed included the rhet and the exclarotive.
An interrobang is meant to replace the usage in writing of an exclamation point and a question mark right next to each other, such as in the sentence, “She said what?!” This sort of formation, and therefore the use of the interrobang, is usually meant either to express disbelief or to convey a sense of excitement about the question being asked. The combination of a question mark and an exclamation point to terminate a sentence has been used for some time in English, not only in informal writing, but also in semi-formal situations such as news headlines. Formally, of course, it is usually considered inappropriate to use more than one terminating mark at the end of a sentence, and so the interrobang has no real place in formal writing.
The interrobang was conceived of by an American advertiser in the 1960s, Martin Speckter, who thought the aesthetic of one typographic symbol would be better than two. The excited or surprised question has often been used in advertising, but even after its creation, the interrobang was rarely used to replace the more common “?!” string.
Despite some early success and adoption, such as its inclusion on a typewriter in the late 1960s, the interrobang never caught on with the world at large. Typographical symbols are rarely adopted, so its failure to become a standard symbol is not a surprise. The fact that the combination it represents is considered by most people to be a poor stylistic construction no doubt also played heavily into its failure. It is, however, not entirely dead; many new font faces include an interrobang; the Unicode system lists it as U+203D, and it can be expressed in HTML as well, using the code ‽, rendering: ‽