The term “et al.” is an abbreviated Latin phrase that means “and others.” Most reference styles make use of this term for in-text citations to aid in readability. The rules for the use of et al. vary among the different reference styles, but the basic guideline is as follows.
The basic rule: When citing a source that has more than two authors, use the first author’s surname followed by the Latin term “et al.” in place of the names of the additional authors.
Examples (these examples are fictional):
Ren et al. (2017) investigated the usage of social media devices among college students in Shanghai.
Some studies investigated the learning components of using social media (Johnson et al., 2014, Aguillar, et al., 2012).
Punctuation with et al.
Just as reference style rules vary regarding how many authors to cite before using et al., the punctuation rules also vary. Your best bet is to consult the author guidelines and look at sample articles for the journal you are submitting your manuscript to. Below are three common stylistic questions concerning et al.
Should a period come after et al.?
Because et al. is an abbreviation of the longer Latin phrase, masculine (et alii), feminine (et aliae), or neuter (et alia), it is usually followed by a period, but some styles will omit the period.
In a parenthetical citation, should a comma follow et al. before the date?
Most styles will include a comma after et al. when followed by a year date; however, others will not. Again, consult the guidelines and sample articles for the journal you are submitting your manuscript to.
Should et al. be italicized?
Some styles will italicize et al., as in et al.; however, this style is becoming less common, just as it is often no longer necessary to italicize other common Latin terms such as in vivo and in vitro.
Consistency matters. Take care to maintain consistency with the style you use for et al. throughout your manuscript. For example, if you are putting it in italics, do so in all instances throughout the manuscript. Consistency in the presentation of your paper suggests to the journal editors that you are just as careful with the particulars of your research.