Ampersand &

The & began as a ligature of the Latin word et, “and.” In many fonts, especially italics, you can still see the E and the t inside it.

The name comes from the schoolroom. Children reciting the alphabet used to end with “… X, Y, Z, and per se and,” meaning “and, the symbol by itself, ‘and.’” Said quickly, that became “ampersand.”

The old abbreviation &c. for “et cetera” is another trace of its Latin roots. You will see it in older documents; today write “etc.”

• Official names: use & when it is part of the name, as in AT&T or Procter & Gamble.
• Set abbreviations: R&D, Q&A, B&B, P&L.
• Tight spaces: headlines, tables, buttons, signs and logos.
• Citations: APA style uses & between author names inside parentheses: (Smith & Lee, 2021). In the running text it switches to “and.”
• Not in regular sentences: “Sales & marketing met on Tuesday” should be “Sales and marketing met on Tuesday.” AP and Chicago both prefer the word.

Look-alikes: ＆ is the fullwidth version for East Asian text. ⅋ (turned ampersand) is a symbol from linear logic, not a decorative ampersand.

• HTML: a bare & starts a character reference, so write it as an entity in markup, especially inside attributes and links. The code table above shows the entity.
• URLs: & separates query parameters, as in ?q=shoes&size=10. A literal & inside a value must be percent-encoded.
• Programming: && is logical AND in C, Java and JavaScript, and a single & is bitwise AND. In shell scripts, a trailing & runs a command in the background.
• Spreadsheets: in Excel and Google Sheets, & joins text: =A1&" "&B1.
• LaTeX: & separates table columns, so type \& to print an ampersand.