Data diddling is a type of cybercrime in which data is altered as it is entered into a computer system, most often by a data entry clerk or a computer virus. Computerized processing of the altered data results in a fraudulent benefit. In some cases, the altered data is changed back after processing to conceal the activity. The results can be huge.[citation needed] They might include adjusting financial figures up or down marginally, or it could be more complex and make an entire system unusable.