Data diddling is a type of cybercrime in which data is altered as it is entered into a computer system,<ref>Template:Cite journal</ref> most often by a data entry clerk or a computer virus.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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.<ref>Template:Cite book</ref><ref>Template:Cite bookTemplate:Dead link</ref> The results can be huge. They might include adjusting financial figures up or down marginally, or it could be more complex and make an entire system unusable.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>