I see "-" this from time to time, but I've never really understood when it's used. When is it used?
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Native speaker’s answer
Rebecca
Here, the hyphen "-" is used to join two words to make a compound adjective to describe a noun. This helps to avoid confusion with the words used. You can also use them to make compound or complex nouns if they contain a preposition, article, or conjunction. Sometimes hyphens act as parentheses to informally indicate extra information within writing. Ex: A very well-behaved boy. => The boy behaves well. = A very well behaved boy. => Without the hyphen, this could be read as a healthy, or "well", and behaved boy. Ex: The information was crystal-clear to me. => compound adjective Ex: The university has state-of-the-art features. => complex noun Ex: We went to visit my mother-in-law this weekend. Ex: My friend - who is on vacation - is coming to visit me. => extra information.