Hyphen-

The hyphen is this line.

-

It’s shorter than an en dash.

You could use the hyphen to make compound words like:

• Mother-in-law
• Best-in-show
• Long-winded
• Short-lived
• Long-term
• Part-time
• Far-flung
• Close-up
• Op-ed
  
  

Or you could just not.

Because do these versions confuse you?

• Mother in law
• Long winded
• Best in show
• Short lived
• Long term
• Part time
• Far flung
• Close up
• Op ed
  
  

The reason to ever use punctuation is to make the meaning clear.

But is it unclear, for example, if I write “rewritten”, as opposed to “re-written”?

I don't think the hyphenated version is any clearer. I might even say it's a little uglier, like a dislocated joint.

Or should that be half-way?

You see, lots of words that were once compound words have lost their bridging hyphen and have become whole words in their own right:
 

• After-noon = Afternoon
• Car-pool = Carpool
• Bed-time = Bedtime
• Store-room = Storeroom
• Note-book = Notebook
• On-line = Online
• Door-knob = Doorknob
• Tea-pot = Teapot
  
  

It's as if the hyphenated version is the engagement two words go through before they unite in marriage. Rather than give any strict rules, for which there will always be antagonists, I say use sensible judgement. Clarity of meaning over everything.

For example, I wouldn't write “motherinlaw”, but both “mother in law” and “mother-in-law” are clear. I would write “re-edit” instead of “reedit”.

I tend not to use hyphens where they’re unnecessary because it’s one less thing to think about.

One final point is that screen readers find it hard to deal with dashes so avoid the hyphen to make your writing more accessible.