Hyphen usage.

[scorza]

Can anyone tell me what the correct rules for the use of hyphens are?

If I have a microphone and I mute it, do I then unmute it or un-mute it?

If water freezes is it because the temperature is sub-zero or subzero?

How do I know when to use a hyphen and when not to?

 

[scorza]

Cheers. Think I know what I have to do now. Why is this stuff so complicated?

 

[scorza]

Oops.

Why should it be hyphenated then? I noticed that he did say 'perhaps should be hyphenated', and not 'definitely should be hyphenated', so what's the reason behind that thinking?

From what I've learnt, sub-zero is hyphenated because "sub" has three letters, unmute isn't hyphenated because "un" has only two letters. As random as that