Typographical error

A typographical error, typo, or fat-finger is a mistake made during the typing process. The term includes errors due to mechanical failure or slips of the hand or finger, but excludes errors of ignorance. Most typos involve simple duplication, omission, transposition, or substitution of a small number of characters.

Though the term "typo" excludes errors of ignorance, it is common to find it used as a euphemism to describe instances of poor spelling, punctuation, or grammar, such as subconsciously typing a homophone. The latter error is occasionally called a thinko.

Marking typos
When using a typewriter without correction tape, typos are commonly overstruck with another character such as a slash. This saves the typist the trouble of retyping the entire page to eliminate the error, but as evidence of the typo remains, it is not aesthetically pleasing.

In instant messaging, users often send messages in haste and only afterwards notice the typo. It is common practice to correct the typo by sending a subsequent message where an asterisk precedes or follows the correct word. For example:

Jane41: "did u ese her?"

Jane41: "see*"

In formal prose it is sometimes necessary to accurately quote text which may contain typos. In such cases, the author will usually write "[sic]" to indicate that an error was in the original quoted source rather than in the transcription.

"Intentional" typos
Certain typos, or kinds of typos, have achieved widespread notoriety and are occasionally used deliberately for humorous purposes. For instance, the British newspaper The Guardian is sometimes referred to as The Grauniad for its alleged frequent typesetting errors in the era before computer typesetting. This practice stems from a joke in the satirical magazine Private Eye claiming that the paper misspelled its own name in the masthead. The magazine continues to refer to the Guardian by this name to this day.

The emergence of Usenet and the World Wide Web as popular forms of mass communication brought many people who are not skilled typists but have a lot to say. Typos are therefore common and some, such as "teh", "pwned", and "pron" have become in-jokes among Internet groups and subcultures. A widely mocked typo is the act of excitedly typing a series of exclamation marks with the failure to properly hold down the shift key (resulting, on a QWERTY keyboard, in strings such as "!!!11"). This is often exaggerated by the replacement of "1" characters with literal "one"s, as in "OMG that is sooo interesting!!!1!one!"

The word "typo" itself is often intentionally cast with letters transposed (especially and particularly as "tyop") in internet chatrooms and other electronic media when the typist is confessing to having incorrectly typed a previous transmission.

Typosquatting
Typosquatting is a form of cybersquatting which relies on typographical errors made by Internet users. Typically, the cybersquatter will register a plausible typo of a well-known website address in hopes of receiving traffic when Internet users mistype that address into a web browser. Deliberately introducing typos into a web page, or into its metadata, can also draw unwitting visitors when they enter these typos in Internet search engines.

Typos in online auctions
Since the emergence and popularization of online auction sites such as eBay, misspelled auction searches have quickly become a gold mine for deal hunters. The concept on which these searches are based is that if an individual posts an auction and misspells its description and/or title, regular searches will not find this auction. However, a search which includes misspelled alterations of the original search term in such a way as to create misspellings, transpositions, omissions, double strike and wrong key errors would find most misspelled auctions. The resulting effect is that there are far fewer bids than there would be under normal circumstances allowing for the searcher to obtain the item for less. A series of third party web sites have sprung up allowing people to find these items.