You may wonder when compound words are to be written as
The conventions of writing compounds in English are simply inconsistent. Thus, a compound like free trade sometimes appears as two separate words separated by space, and sometimes as free-trade, a single hyphenated word. cf. also Wordformation, Word Formation, Word-Formation
The hyphen is used when a compound has been newly created or is not widely current.
When a compound has gained a certain currency or permanence, it is often spelled closed up.The word blackboard, when it was first created, was written black-board, a spelling found in texts from the first part of this century.
The rule in English for spelling multiword compounds, such as community center finance committee, is not to write them as a single word. Further examples are student film society, Lakeside Grammar School
Certainly we should like to treat firewood, fire-engine and fire insurance in a similar way, despite the inconsistent use of word spaces and hyphens in the English orthographical system.
Compounds may be shortened via their written form, especially if they appear as a sequence of orthographic words. A sequence is formed by adding together the initial letters of these written words (initialisms). Two types are usually distinguished, acronyms and abbreviations.
Acronyms are pronounced as words (also called syllable words).
Abbreviations, which consist for the most part of three capital letters, are pronounced as a series of letters (letter words). Examples are:
Acronyms Abbreviations scuba BP (British Petroleum, beautiful people US (self-contained underwater CAD breathing apparatus) Aids VIP dinky VSOP (very superior old pale => brandy) NIMBY UFO RAM AI ROM MIT (Massachusetts Institute of Technology) radar DIY (radio detection and ranging)