Punctuation Rules About the Ampersand
The ampersand is a symbol that is used as an abbreviation for the word "and." While it's a common abbreviation, it should not be overused. Aside from informal notes and lists, the ampersand is used in academic citations and some company names. It should not be used to substitute for "and" in formal or academic writing.
1 Ampersands in Company Names
The ampersand is commonly used in company names and logos, either for stylistic reasons or to save space. Companies that use an ampersand in their name include Procter & Gamble, Johnson & Johnson, Arm & Hammer, Tiffany & Co. and AT&T. When the ampersand is used between initials or single letters, as with AT&T, there is no space before or after the symbol.
2 Ampersands in Academic References
In some academic citation styles, such as the American Psychological Association format, the ampersand is used between author names when citing works with two or more authors. For example, an APA in-text citation would look like this: "Giraffes' long necks are an advantage, allowing them to reach vegetation that is high up (Isbell & Young, 1991)." On the References page, the ampersand would be seen in the citation like this: Isbell, L. A., & Young, T. P. (1991). Sex differences in giraffe feeding ecology: energetic and social constraints. Ethology, 87, 79-89. On the References page, the ampersand is preceded by a comma.