People are often unsure about how to write abbreviations. The main areas of uncertainty are:

• whether to write abbreviations with capital letters

• whether to use full stops

• when to use apostrophes.

Here’s a quick-reference guide to help you get it right.

There are several kinds of abbreviation: the way an abbreviation is written usually depends on the category to which it belongs. The categories are listed below.

Acronyms

Acronyms are words formed from the initial letters of other words and pronounced as they are spelled, not as separate letters. Examples include:

• Most acronyms can be written as capital letters or with only an initial capital letter.

• Some acronyms are so established that they are now ‘normal’ words, generally used without conscious awareness of their original full form. These words should be written in lower-case letters. Examples include:

Contractions

Contractions are a type of abbreviation in which letters from the middle of the word are omitted. Examples include:

A contraction can also be an abbreviated form of more than one word, for example:

• You do not need to use a full stop at the end of contractions, because the last letter of the original word is still present.

• In contractions that represent more than one word, the letters that have been omitted should be replaced with an apostrophe.

Initialisms

Initialisms are abbreviations which consist of the initial (i.e. first) letters of words and which are pronounced as separate letters when they are spoken. Examples include:

• You do not need to put full stops after the letters in an initialism. Sometimes, especially in American English, certain initialisms may include full stops if that is the preferred style of a particular writer or publisher. For example, the forms US and U.S.are both acceptable, as long as one or the other is used consistently within a piece of writing.

• When you are forming the plural of an initialism, you do not need to use an apostrophe, for example:

• Note that the possessive form of initialisms is formed in the usual way, with an apostrophe + s:

Shortenings

Shortenings are abbreviations in which the beginning or end of the word has been dropped. In some cases both the beginning and the end have been omitted. Examples include:

In some cases, the shortening involves a slight spelling change, as with bike and telly.

These shortenings are now an accepted part of the language. In fact some of the original, longer forms tend to be used only in formal or technical writing. It would sound rather odd, for example, to describe a person as suffering from influenza unless you were writing in a scientific context.

• You do not need to use an apostrophe in shortenings to show that letters have been omitted.

• You should only use a capital letter if the original form also starts with a capital letter, for example:

• You do not need to use a full stop unless the shortening is one created specifically for use in writing, for example: