Strikethrough

Strikethrough, or strikeout, is a typographical presentation of words with a horizontal line through their middle. Less common alternative forms of strikethrough are an X or a forward slash typed over each letter.

In medieval manuscripts, where strikethrough appears as a red line over the otherwise black text, the purpose is to highlight the text, giving it emphasis. In modern texts, the purpose is the opposite; it indicates removed text. Contrary to censored or redacted texts, the words remain readable.

Strikethrough primarily appears as a horizontal line across the middle of words. This appearance is the easiest to achieve by hand, as it only requires one continuous stroke with a pen, pencil, or other writing instruments. Less common forms of strikethrough include drawing an X (cross) or / (solidus) over each letter of the word. To strike long words or phrases, this method is cumbersome to produce by hand, but may be the preferred method for single letters, where the horizontal line does not produce the necessary visibility, and could be missed.

On personal computers, double strikethrough is an option in some word processors, spreadsheets, presentation software, and graphics software, e.g., in Microsoft Office, Collabora Online and LibreOffice. In Japan, double strikethrough is conventionally used because in complex kanji, a single strikethrough may be missed or confused with a stroke in the character. Otherwise, there is no generally agreed meaning of double strikethrough.

In modern prose, however, strikethrough is primarily used to mark text as a mistake or to be removed. Word processors capable of tracking changes use strikethrough to on deleted words.

Historically, however, strikethrough was not even the primary way to mark errors. Errors were more commonly marked by placing dots under letters to be ignored (Latin: punctum delens). In medieval manuscripts such as the Domesday Book, "strikethrough" of text with red ink often functions as highlighting similar to modern underline.

Wordstar supported the "strikeout" decoration since version 3.0 in 1982, although the functionality may have been present in earlier versions. Wordstar was launched in 1978. It dominated the personal computer market as the most popular word processing program until 1985, when WordPerfect gained dominance. All word processors with functionality beyond basic editing include strikeout, though the prefer the term "strikethrough".

Early versions of the Hypertext Markup Language (HTML) specify the <strike> or <s> tags for rendering text with strikethrough. These tags, however, are purely decorative. In 1999, the HTML standard version 4.01 deprecated them in favor of the <del> tag, a semantic element for marking deleted text. Web browser and other user agents often render the contents of this tag with strikethrough. In the HTML5 draft, the <s> is redefined as a semantic tag that marks its text that as no longer correct. The <del> remains unchanged and still specifies deleted text.