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

full form
National Broadcasting Company
military policeman
United Nations
African National Congress
USAUnited States of America
United Kingdom
compact disc
  • For initialisms, you do not need to put periods after the letters. Although the absence of periods is the predominant style, sometimes (specifically in American English), certain initialisms may include periods if that is preferred by the 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: 
e.g., the MPs escorted us the rest of the way.
e.g., I bought some new CDs today.
  • Note that the possessive form of initialisms is formed in the usual way, with an apostrophe + s:
an MP’s detail
(i.e., the detail of an MP)
a report on the MPs’ activities
(i.e., the activities of the MPs)
the CD’s subtitle
(i.e., the subtitle of the CD)


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Grammar and usage