et al.

Latin for “and others.” Citation styles use it to shorten a list of authors, but each style starts using it at a different point.

Write it with a period after “al” (it’s short for alii) and no period after “et”.

(Martin et al., 2020)

When to use it:

• APA 7: three or more authors, in every in-text citation, including the first. The reference list still names the authors in full (up to 20).
• MLA 9: three or more authors, in parenthetical citations and the Works Cited list. In your own sentences, say “and colleagues” or “and others” instead.
• Chicago 18th edition: three or more authors in notes and author-date citations. The bibliography or reference list names up to six authors; for seven or more, list the first three, then “et al.”