Abbreviation

Initialisms are a form of abbreviation in which a phrase is abbreviated to the first letter of each word in the phrase; familiar examples include

• CPA for Certified Public Accountand
• CBS for Columbia Broadcasting System
• KJV for King James Version.

They are distinguished from acronyms in that initialisms are pronounced as individual letters, while acronyms are pronounced as if the letters spelled out a word (which they may in some cases do). Both initialisms and acronyms are defined by custom; sometimes they do not strictly follow the rule of using every initial, or only the first initial. Unimportant words may be omitted, and particularly in the case of acronyms a certain amount of creativity may be employed.

• FBI for Federal Bureau of Investigation

Examples of acronyms include:

• USA PATRIOT Act for Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act
• TULIP for Total Depravity, Unconditional Election, Limited Atonement, Irresistible Grace, and Perseverance of the Saints (the core tenets of Calvinism.

(The use of the word "acronym" to include initialisms as well as acronyms is imprecise, but increasingly accepted).