Hyphenate when:
* The two words act as a single unit modifying a noun: The two words work together to describe the noun.
* The words precede the noun: The hyphen helps clarify that the two words are a unit.
* The words could be misinterpreted without the hyphen: Hyphens prevent confusion about meaning.
Examples:
* well-known author (The author is well known.)
* up-to-date information (The information is up to date.)
* long-term goal (The goal is long term.)
* state-of-the-art technology (The technology is state of the art.)
* two-thirds majority (The majority is two thirds.)
Do not hyphenate when:
* The words follow the noun: The words are part of the noun phrase.
* The words are a standard compound adjective: The words are so commonly used together that they are considered one word.
Examples:
* The author is well known.
* The information is up to date.
* The goal is long term.
* The technology is state of the art.
* The majority is two thirds.
Key Points to Remember:
* Context is key: Consider how the words function within the sentence.
* Standard compound adjectives are not hyphenated: "high school," "middle age," "low income."
* If in doubt, use a dictionary: Dictionaries can clarify the proper use of hyphenation.
Note: Hyphenation rules can be complex and sometimes contradictory. If you're unsure about a specific case, it's always best to err on the side of caution and use a hyphen.