The <abbr> tag is used when you are typing abbreviations on your pages but still want spiders, crawlers, robots, whatever you like calling them, to understand abbreviations that are on your pages. Some browsers show the viewer the full word when he hover the mouse over the abbreviation. Again the difference between acronym and abbreviation is that acronym is usually the first letters of multi-words expression like: FBI, USA, UN, etc. and abbreviation is a shorter way of writing a word like: Capt., sgt., pop., etc.

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