Hyphen "-" can be confusing if you're unsure when do you need to use them.
Consider these phrases:
- The boy is seven-years-old
- The ideas are out-of-date
- He's just a seven-years-old boy
- Some out-of-date and messed-up ideas
- My life-changing experience
- Write a three-word sentence
Which of the sentences above is correct?
One tip to know when to use hyphen is to look for compound adjective. Adjectives are words that modify/describe the noun or subject.
So beautiful hat, furry dog, expensive gadgets are examples of adjectives.
Compound adjectives is a phrase, made up of two or more words that modifies a noun. And Compound adjectives before a noun get hyphenated.
So from the list above, the following are correct:
- He's just a seven-year-old boy
- Some out-of-date and messed-up ideas
- My life-changing experience
- Write a three-word sentence
On the contrary, when compound adjectives stand own its own, when they don't precede a noun, they don't get hyphenated:
- The ideas are out of date.
- The boy is seven years old.
There are other words where it may not be immediately clear if there should be hyphen between them:
- Work place
- Long time (adjective)
- Life time
- Fire works
- Weather man
- Mean time
- Some times
- Touch down
The best thing you can do if you're not sure is to just look up the dictionary!