What is an abbreviation?

An abbreviation is a shortened form of a written word or phrase. Abbreviations may be used to save space and time, to avoid repetition of long words and phrases, or simply to conform to conventional usage.

The styling of abbreviations is inconsistent and arbitrary and includes many possible variations. Some abbreviations are formed by omitting all but the first few letters of a word; such abbreviations usually end in a period: Oct. for October, univ. for university, and cont. for continued. Other abbreviations are formed by omitting letters from the middle of the word and usually also end in a period: govt. for government, Dr. for Doctor, and atty. for attorney. Abbreviations for the names of states in the U.S. are two capitalized letters, e.g., AR for Arkansas, ME for Maine, and TX for Texas.

Acronyms are abbreviations formed from the initial letters of an expanded phrase and usually do not include periods: PR for public relations, CEO for chief executive officer, and BTW for by the way. Some acronyms are pronounced as words: FEMA for Federal Emergency Management Agency and NATO for North Atlantic Treaty Organization. Although some people assert that all acronyms not pronounced as words, such as EPA for Environmental Protection Agency, be referred to as initialisms, the term acronym is in fact applied to both.

What's the difference between an abbreviation and an acronym?

Some people are unsure of whether to call ASAP or appt abbreviations or acronyms. Both abbreviation and acronym are used to refer to a shortened form, but an acronym is a shortened form of a phrase and is usually made up of the initial letters of that phrase. For example, NATO comes from “North Atlantic Treaty Organization,” and ASAP comes from “as soon as possible.” Abbreviations, on the other hand, can be shortened forms of words or phrases, and need not necessarily be made up of the initial letters of either. ASAP and appt (for appointment) are both considered abbreviations, but only ASAP is an acronym. Acronyms are a type of abbreviation.