Fat finger, or "fat finger syndrome", a slang term, refers to an unwanted secondary action when typing. When one's finger is bigger than the touch zone, there can be inaccuracy in the fine motor movements and accidents occur. This is common with touchscreens. One may hit two adjacent keys on the keyboard in a single keystroke. An example is "buckled" instead of "bucked", due to the "L" key being next to the "K" key on the QWERTY keyboard, the most common keyboard for Latin-script alphabets.
A typographical error (often shortened to typo), also called misprint, is a mistake made in the typing process (such as a spelling mistake) of printed material.
The term includes errors due to mechanical failure or slips of the hand or finger, but excludes errors of ignorance, such as spelling errors, or the flip-flopping of words such as "than" and "then".
Most typos involve simple duplication, omission, transposition, or substitution of a small number of characters.