By Judy Vorfeld
If you do much reading, or are in certain professions, you not only come across the expression et al., but know what it means. Et al. used to be used just in the U.S. in legal documents, but for many years it’s been used in most bibliographies as well. And other places.
It’s used, says Wikipedia, similarly to et cetera (“and the rest”), to stand for a list of names.
According to Chicago Manual of Style, 5.220, you say et al. with a period following “al.” This is the abbreviated form of et alii (“and others”); the others are people, not things. Since al. is an abbreviation, the period is required.
Tip: (6.20) says et al. stands for et alia (neut.), et alii (masculine), and et aliae (feminine). Also, no need to italicize et al. in normal prose.