Acronyms and initialisms
Most people use the term acronym to apply to both acronyms and initialisms, but there is a difference. An acronym is an abbreviation of initial letters that forms a new word, such as PACKO, which stands for purpose, audience, context, key messages and outcome. An initialism is an abbreviation of initial letters that does not form a new word, for example, AFL.

In some cases, such as ADSL, spelling out the name (Asymmetrical Digital Subscriber Line) doesn't add much to the meaning and you're best to provide a brief description instead — ADSL (high-speed internet).

Become part of the language?
Some abbreviations, such as 'Anzac' and 'scuba' have become so widely known that they are seldom explained or spelt out, in fact, most people don't even know what they stand for 'Australian and New Zealand Army Corps' and 'self-contained underwater breathing apparatus'. 

The problem arises on where to draw the line. I think people too often assume you know their shortcuts, such as 'UI' (User Interface) and 'apps' (applications) when you don't.

If you're in doubt about your terms, ask someone outside your industry or spell them out — noone is going to offended if you spell out or explain your terms, but it is very off-putting to see a page or PowerPoint presentation full of abbreviations you don't understand.

Need a context and explanation
Sometimes explaining your terms doesn't solve the problem for non-technical readers. For example, the following sentence is appropriate for technical readers, but not for a general audience:

vLAN packets carry a standard IP header, with source and destination IP addresses, so a vLAN router forwards them in the normal way--but only on the vLAN.  http://www.viewsletter.com

If this were for a wide audience the writer would have to give us a general overview for it to make any sense.

Tips for writing about technical subjects for multiple audiences:

• Don't assume people will understand your technical terms just because you do.
• Write a non-technical executive summary if you have multiple audiences.
• Provide a glossary of terms.
• Use diagrams.
• Include graphics.
• If writing for the web, you could hyperlink to a separate page or website for more technical readers.
• If using a PDF file, write a two-three line summary and give the file size.
• Spell out all terms, not just the obvious ones. It's amazing how many documents spell out some, but not all terms.
• Spell out or explain terms in PowerPoint presentations as well as print and web documents.
• Put key information in boxes. During WW11, aircraft designers found that new pilots often made errors reading labels on control panels and discovered that drawing a box round a piece of text made it easier to read. (http://www.viewsletter.com).

Further reading
If you enjoyed this article, you may also wish to read:
Bored with board papers?
Writing executive summaries
Editing and proofreading tips
Writing endings
First, second and third person
Trouble getting started
Readability formulas
Make numbers manageable
What is irony?
Writing recommendations
Writing quotations

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