When we are use hyphens?

Hyphens are used to connect Words or parts of Words, particularly in compound adjectives (e.g., "well-known author") and to join prefixes to proper nouns (e.g., "un-American"). They also help clarify meaning by linking Words in phrases (e.g., "two-thirds"). Additionally, hyphens are used in compound numbers from twenty-one to ninety-nine and in fractions (e.g., "one-third"). Always check for specific style guidelines, as usage can vary.