Writing Style – Abbreviations: Acronyms and Initialisms

BizWritingTip reader: “In a publication we are currently editing, the first program/service sometimes is written with the first letter of each word capitalized and then the acronym in all caps. At other times, it is written all small caps with the acronym in caps. Which way is correct?”

BizWritingTip reader: It is often easier to shorten a long title by using an abbreviation — a shortened form. Some abbreviations are acronyms; some are initialisms. An acronym is an abbreviation pronounced as a word. It is formed from the first letter of each word.

Examples (acronyms)
AIDS (acquired immune deficiency syndrome)
NATO (North Atlantic Treaty Organization)

An abbreviation made up a group of initial letters that are each pronounced is called an initialism.

Examples (Initialisms)
CD (compact disc)
YMCA (Young Men’s Christian Association)
a.m. (ante meridian)

Whether you are using an acronym or an initialism, if you know your readers understand the term, there is no need to explain it.

However, if you are introducing a new program or service or have any doubt your reader will know the abbreviated form, it is best to write the name in full (capitalizing the initial letters only) and then follow it with the abbreviation in brackets.

Golf Life Management System (GLMS)

Note: Almost all abbreviations made up single lowercase letters require a period after each initial. But do not put a space after the first period.


Abbreviations made up of all capital letters do not require periods.


Exceptions: Keep the periods in the abbreviations of geographical locations (B.C., U.S.), academic degrees (M.Sc.), expressions (A.D., V.P.), and in the names of products and organizations if the company uses them.