An initialism is a set of initials that stands for a group of words, as in the following examples:

When using an initialism more than once in the same piece of writing, give the full form plus the initialism in brackets for the first mention, then use the initialism alone for all later mentions:

Note that full stops are not used to separate the letters within initialisms.

Often, the initials or shortened form of a long word or name will form a pronounceable word. This is called an acronym. Many acronyms are based on names of organisations:

Some much-used acronyms can be absorbed into the language over time:

Because usage is ever-evolving, there is no single rule that applies to how acronyms should be capitalised. Check organisational sources or a dictionary for guidance.

Note that full stops are not used to separate the letters within acronyms.

Contractions are words that are abbreviated by omitting one or more letters (e.g., 'gov't' for 'government'), or words that are formed by joining two words and omitting one or more letters. An apostrophe marks the place of the omitted letters. Note that contractions are inappropriate in formal writing; use the full form instead.

In academic writing, Latin abbreviations (such as 'e.g.', 'i.e.', 'etc.' and 'vs.') are generally only used in reference citations and within parentheses. In the text itself, the full English form is preferred. An exception is 'et al.', which is used when citing sources in the text and in parentheses. Note it is not necessary to italicise common Latin terms, such as those above.

English alternatives should be preferred over less commonly used Latin terms (such as 'supra', 'infra', 'pro tem.' and 'cf.'), unless instructed otherwise.

In work where it is conventional to use abbreviated scientific terms, give the full form and the abbreviation (in parentheses) at first mention, and the abbreviation alone in later mentions: