The incorrect spelling of words on the web, is often referred to as a mistype. Mistyping a word is a surprisingly common problem, even for the most basic and heavily used words, typed millions of times a day. Some of these errors are due to bad keyboard technique, and some of them are due to poor spelling skills.

Sometimes where just in a rush and attempt to type a word at breakneck speed. Mistyping a word seems such an innocent act, without a great deal of consequence, but savvy domain traders have cashed in other peoples mistakes for years now. It's quite common for a domain trader to hunt down popular websites, check every variation of a mistype that they think is probable, and "park" that site at one of the PPC networks, and make money on the adverts. Sometimes this is a dollar a month, sometimes its hundreds of dollars.

From a webmasters point of view, you need to study mistypes so that can cover the common mistypes for your keywords, and perhaps so can hunt down and buy the domains that are likely to steal your traffic long term. Keep in mind however that popular search terms, with popular mistypes generate a significant amount of revenue for there owners over the course of a year. Its likely to cost you a pretty penny to buy those domains.